JP2006219510A - Flame-retardant olefinic polymer composition having excellent electrical insulating property - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant olefinic polymer composition having improved excellent electrical insulating properties by compounding a small amount of an improving agent for electrical insulating properties with a non-halogen flame retardant. <P>SOLUTION: The flame-retardant olefinic polymer composition is obtained as follows. An olefinic polymer is compounded with aluminum compound-containing silicate particles prepared by grinding and mixing siliceous particles having ≥90 wt.% content of silicic acid (expressed in terms of SiO<SB>2</SB>) and a chemical compositional ratio represented by formula (1) SiO<SB>2</SB>-nAl<SB>2</SB>O<SB>3</SB>(1) (wherein, n is a number of 0.001-0.01) with aluminum hydroxide and/or calcined kaolin and the non-halogen flame retardant. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flame retardant olefin polymer composition containing a non-halogen flame retardant such as magnesium hydroxide, and more specifically, a flame retardant olefin polymer with improved electrical insulation. Relates to the composition.

  In general, an olefin polymer such as a polyolefin or an olefin copolymer is excellent in electrical insulation as compared with a vinyl polymer such as polyvinyl chloride, but has a drawback of low flame retardancy. For this reason, a flame retardant is mix | blended with the olefin type polymer, and the flame retardance is improved.

  Halogen compounds have been used as such flame retardants, but there is a problem of generating halogen gas harmful to the human body in the event of a fire. In recent years, non-halogen flame retardants such as hydrated alumina and magnesium hydroxide Has come to be used.

  However, non-halogen flame retardants have the property of being easy to absorb water. Therefore, although the problem of the generation of halogen gas has been solved, the electrical insulation that is a characteristic of olefin polymers is reduced. There is.

In order to solve such drawbacks, Patent Document 1 proposes blending calcined clay and silica into an olefin polymer together with a non-halogen flame retardant.
JP-A-11-222539

  In the above-mentioned Patent Document 1, a combination of fired clay and silica is used as an electrical insulation improver. However, such a combination is not sufficient in its electrical insulation improvement effect, and may be satisfactory, for example. In order to obtain electrical insulation, it is necessary to mix a considerably large amount of calcined clay and silica. Therefore, there arises a problem that characteristics of the olefin polymer such as whiteness, elongation, and tensile strength are deteriorated. ing.

  Accordingly, an object of the present invention is to provide an olefin polymer composition having an improved electrical insulation property by blending a small amount of an electrical insulation improver with a non-halogen flame retardant.

According to the present invention, the content of silicic acid (SiO ₂ equivalent) is 90% by weight or more, and the following formula (1):
SiO ₂ · nAl ₂ O ₃ (1)
Where n is a number from 0.001 to 0.01.
An aluminum compound-containing silicate particle obtained by grinding and mixing silica-based particles having a chemical composition ratio represented by the following: aluminum hydroxide and / or calcined kaolin, and non-halogen flame retardant An olefin polymer composition characterized by being blended with a polymer is provided.

In the olefin polymer composition of the present invention,
(1) The aluminum compound-containing silicate particles contain aluminum hydroxide and / or calcined kaolin in an amount of 1 to 100 parts by weight per 100 parts by weight of the silica particles.
(2) The aluminum compound-containing silicate particles are contained in an amount of 0.01 to 10 parts by weight and the non-halogen flame retardant is contained in an amount of 5 to 200 parts by weight per 100 parts by weight of the olefin polymer.
(3) the non-halogen flame retardant is magnesium hydroxide;
Is preferred.

  In the present invention, it contains an aluminum compound obtained by grinding and mixing silica-based particles having a specific composition containing a trace amount of alumina represented by the formula (1), and aluminum hydroxide and / or calcined kaolin. It is an important feature that silicate particles are blended in an olefin polymer together with a non-halogen flame retardant as an electrical insulation improver. That is, such an electrical insulation improver is an extremely small amount (for example, 0.01 to 10 parts by weight per 100 parts by weight of the olefin polymer) and an olefin polymer composition containing a non-halogen flame retardant. As a result, it is possible to effectively avoid deterioration of characteristics such as whiteness, elongation, and tensile strength, as shown in Examples described later.

(Electrical insulation improver)
In the present invention, aluminum compound-containing silicate particles obtained by grinding and mixing silica-based particles and aluminum hydroxide and / or calcined kaolin are used as an electrical insulation improver.

The above silica-based particles, the silicate (SiO ₂ equivalent) fraction containing 90 wt% or more and the following formula (1):
SiO ₂ · nAl ₂ O ₃ (1)
Where n is a number from 0.001 to 0.01.
As shown in the formula (1), it contains a trace amount of an alumina component. Particles containing such a large amount of silicic acid and satisfying the chemical composition ratio (SiO ₂ / Al ₂ O ₃ ratio) of the formula (1) should be adjusted to a very fine and sharp particle size distribution. When such particle size-adjusted particles are used after being ground and mixed with aluminum hydroxide and / or calcined kaolin, an excellent effect of improving electrical insulation can be obtained with a remarkably small blending amount.

  Such silica-based particles have extremely good pulverization properties, and are finely pulverized using a jet mill or the like and then dried to adjust the particle size to those having extremely fine particles and a sharp particle size distribution. Can do. For example, as measured by a laser scattering method, the volume-based median diameter is 0.1 to 1 μm, and there are substantially no particles having a particle size of 10 μm or more, and further, the particle size is 0.01 μm or less. It is preferable to have a particle size distribution that does not substantially exist, and by using such a fine particle having a sharp particle size distribution, the handling property and the dispersibility to the polymer become good.

  For example, in the above formula (1), when the number of n (number of moles of alumina per mole of silica) is outside the above range, the pulverizability of the particles is impaired. It becomes difficult to adjust the particle size so as to have a particle size distribution, the uniform dispersibility to the polymer is impaired, and it becomes difficult to stably exhibit the effect of improving electrical insulation.

  For example, silica sol and an aluminum sulfate solution are mixed so as to satisfy the quantitative ratio of the above formula (1), and the silica particles are co-precipitated by adjusting the pH to about 3 at room temperature and atmospheric pressure. It can be prepared by washing with water and drying. It can also be prepared by acid treatment of smectite clay such as acid clay.

  In the present invention, the silica-based particles are usually amorphous, but some of the crystalline structure may remain, and are generally used in an unfired state. However, if necessary, it can be used after firing.

Further, the above silica-based particles usually preferably have a BET specific surface area in the range of 50 to 300 m ² / g. The electrical insulation improvement effect shows a tendency to increase as the BET specific surface area increases, but if the specific surface area becomes too large, it becomes bulky and the dispersibility to the polymer tends to decrease. Preferably there is.

  The above silica-based particles are mixed with aluminum hydroxide and / or calcined kaolin to obtain aluminum compound-containing silicate particles for use in the present invention. In the present invention, it is important to mix by grinding. If the mixture is simply dry, a sufficient effect of improving electrical insulation cannot be achieved. For example, as shown in Comparative Example 5, when the silica-based particles and the calcined kaolin are blended into the olefin polymer by simply dry mixing instead of grinding and mixing, the electrical insulation is the same amount. This is considerably inferior to the added composition of the present invention (Example 2). The detailed reason why the aluminum compound-containing silicate particles obtained by such grinding and mixing exhibit a high effect of improving electrical insulation is unknown, but is presumed as follows. That is, the above silica-based particles themselves show a high electrical insulation improvement effect, and when this is mixed with aluminum hydroxide and / or calcined kaolin, it is pulverized by pulverization, and the bonds in the crystal structure are broken. It is considered that the basic exchange capacity is increased, and an electrolytic substance such as sodium is trapped by adsorption or the like, and as a result, it is considered that a high electrical insulation improvement effect is exhibited.

  In the present invention, the mixing ratio of silica-based particles and aluminum hydroxide and / or calcined kaolin is 1 to 100 parts by weight of aluminum hydroxide and / or calcined kaolin per 100 parts by weight of silica-based particles. Preferably, when the mixing ratio is outside this range, the effect of improving electrical insulation tends to be low.

  The grinding method may be either dry or wet, but wet grinding is particularly preferred. As an example, it is obtained by mechanochemically reacting silica-based particles with aluminum hydroxide and / or calcined kaolin in the presence of water. The mechanochemical reaction is a reaction under a condition in which mechanical grinding force is applied to silica-based particles and aluminum hydroxide and / or calcined kaolin. Generally, reactions such as ball mill, tube mill, vibration mill, and bead mill Using the apparatus, the reaction is carried out at the lowest possible temperature, generally not higher than 70 ° C., in particular 15 to 50 ° C.

  The aluminum compound-containing silicate particles obtained as described above are blended, for example, in an amount of 0.01 to 10 parts by weight, particularly 0.1 to 5 parts by weight per 100 parts by weight of the olefin polymer described later. By such a small amount of blending, it is possible to prevent a decrease in electrical insulation due to blending of the non-halogen flame retardant described below, and to significantly increase electrical insulation. In particular, since electrical insulation can be enhanced by blending in a small amount, deterioration of characteristics of the olefin polymer such as whiteness, elongation and tensile strength can be effectively avoided. In particular, the weight ratio (aluminum compound-containing silicate particles: non-halogen flame retardant) to a non-halogen flame retardant (preferably magnesium hydroxide) described later is 1: 0.5 to 1: 20000 (preferably 1: 2 to 1: 2000), the elongation and tensile strength can be maintained at extremely high values.

  If necessary, the above-described aluminum compound-containing silicate particles can be surface-treated with a higher fatty acid salt (especially a calcium salt) to further improve dispersibility and use. In this case, the higher fatty acid salt is preferably used in a range of 0.5 to 30% by weight per aluminum compound-containing silicate particle. For the surface treatment, other than the higher fatty acid calcium, for example, higher fatty acids other than calcium and salts thereof, polyhydric alcohols or partial esters thereof (dipentaerythritol, etc.) may be used.

  As higher fatty acid calcium, saturated fatty acids having 10 to 22 carbon atoms, particularly 14 to 18 carbon atoms, such as capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, arachidic acid, etc. Calcium salts of unsaturated fatty acids such as fatty acids, Linderic acid, Tuzuic acid, Petrothelic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid and the like are used. Of these, calcium stearate is preferred. Of course, the fatty acid may be a mixed fatty acid such as beef tallow fatty acid, coconut oil fatty acid, or palm oil fatty acid.

(Non-halogen flame retardant)
In the present invention, as the non-halogen flame retardant, those known per se, such as hydrated alumina, magnesium hydroxide, phosphorus compounds, zinc borate, zinc stannate, zinc hydroxystannate and the like can be used. However, the excellent effect of the present invention is manifested particularly when magnesium hydroxide is used. In other words, magnesium hydroxide has a high water absorption and a large decrease in electrical insulation due to water absorption. However, in the present invention, by adding a small amount of the above-mentioned aluminum compound-containing silicate particles, the electrical insulation is remarkably improved. Because you can. Furthermore, in the present invention, magnesium hydroxide is most preferable from the viewpoint of mechanical properties such as elongation and tensile strength.

Such a non-halogen flame retardant is based on 100 parts by weight of the polyolefin polymer.
It is used in an amount of 5 to 200 parts by weight, preferably 10 to 200 parts by weight. In particular, when magnesium hydroxide is used as the non-halogen flame retardant, the most excellent mechanical properties can be secured when the amount ratio with the aluminum compound-containing silicate particles is in the above-described range.

(Olefin polymer)
As the polyolefin polymer in which the above-described aluminum compound-containing silicate particles and non-halogen flame retardant are blended, various resins, rubbers or elastomers made of olefin homopolymers or copolymers can be used. Specifically, homopolyolefins such as low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, or ethylene, propylene, 1-butene, 4-methyl-1-pentene, etc. Random or block copolymers of these α-olefins, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers and the like are used.

(Other ingredients)
In the olefin polymer composition of the present invention, various compounding agents can be blended in addition to the aforementioned aluminum compound-containing silicate particles and non-halogen flame retardants, for example, various antioxidants and antistatic agents. Etc. may be blended in an amount known per se.

The invention is further illustrated by the following examples. In addition, the test method performed in the Example was performed as follows. For ethylene-vinyl acetate copolymer (EVA), Sumitomo Chemical's Evaate H2011 (vinyl acetate content (VA) 15%) is used. For magnesium hydroxide (Mg (OH) ₂ ), Kyowa Chemical Kisuma 5A is used. It was.

(1) Particle size measurement
The average particle size was measured using a Particle Size Analyzer Model LS13 320 manufactured by Coulter.

(2) Electrical insulation (VR)
A sheet was prepared under the following composition and preparation conditions to obtain a test piece, and the volume specific resistance value at 30 ° C. or 60 ° C. of the sample sheet was measured according to JIS.K.6723. The measurement was carried out by leaving the test piece for a whole day and night in a laboratory environment, and holding it at each measurement temperature for 1 hour.
<Combination>
Parts by weight
EVA (VA = 15%): 100
Mg (OH) ₂ : 50
Insulation improver: see Table 1 or 2

<Test specimen preparation>
After kneading at 125 ° C. for 5 minutes, pressing was performed at 150 ° C. for 5 minutes to prepare a sheet (test piece) having a thickness of 1 mm.

(3) Sheet Whiteness A sheet prepared under the same conditions as in (2) above was measured using a ND-1001DP type colorimetric difference meter manufactured by Nippon Denshoku Co., Ltd. The whiteness is indicated by Hunter Whiteness (WB).

(4) Tensile elongation and strength Sheets prepared under the same conditions as in (2) above were measured according to JIS C 3005.

(Sample preparation 1)
Acid clay acid treated product (Mizusawa Industrial Chemicals, Ltd.: SiO ₂ minutes 93wt%, Al ₂ O ₃ minutes _{1.5wt%, Al 2 O 3 /} SiO 2 molar ratio (n) = 0.0095) and 70 g, calcined kaolin (SATINTONE SP- 33) 30g was charged into a 1.5L pot mill filled with 600ml of 2mmφ alumina balls together with 300ml of ion-exchanged water, and run at 100 rpm for 12 hours for grinding and mixing treatment. The slurry was transferred to a stainless steel vat and evaporated to dryness at 110 ° C. overnight. The obtained dried cake was pulverized by a sample mill, and further finely pulverized by a jet mill (PJM-100SP type) manufactured by Nippon Pneumatic Co., Ltd. to obtain a sample. This sample is designated as S-1. The average particle diameter of this sample (S-1) is 0.40 μm. A particle size distribution diagram is shown in FIG.

(Sample preparation 2)
Using 85 g of acid clay treated acid sample used in sample preparation 1, 10 g of calcined kaolin (SATINTONE SP-33) and 5 g of aluminum hydroxide (H-42 made by Showa Denko), perform the same preparation as sample preparation 1. A sample was obtained. This sample is designated as S-2.

(Sample preparation 3)
70 g of acid-treated acid clay used in Sample Preparation 1 and 30 g of calcined kaolin were simply dry-mixed without grinding and mixing to obtain a sample. This sample is designated as H-1.

(Examples 1-3)
As an insulation improver, S-1 was added in the amounts shown in Table 1, and the resin was evaluated. The results are shown in Table 1.

Example 4
S-2 was added as an insulation improver, and the resin was evaluated. The results are shown in Table 1.

(Comparative Example 1)
The resin was evaluated without adding an insulation improver (blank). The results are shown in Table 2.

(Comparative Examples 2 to 4)
Sintered kaolin (SATINTONE SP-33) was added as an insulation improver in the amounts shown in Table 2, and the resin was evaluated. The results are shown in Table 2.

(Comparative Example 5)
The resin was evaluated by adding H-1 as an insulation improver. The results are shown in Table 2.

It is a figure which shows the particle size distribution of the aluminum compound containing silicate particle | grains (sample S-1) used by this invention.

Claims (4)

Contains 90% by weight or more of silicic acid (SiO ₂ equivalent), and the following formula (1):
SiO ₂ · nAl ₂ O ₃ (1)
Where n is a number from 0.001 to 0.01.
An aluminum compound-containing silicate particle obtained by grinding and mixing silica-based particles having a chemical composition ratio represented by the following: aluminum hydroxide and / or calcined kaolin, and non-halogen flame retardant as olefin An olefin polymer composition characterized by being blended with a polymer.   The olefin polymer according to claim 1, wherein the aluminum compound-containing silicate particles contain aluminum hydroxide and / or calcined kaolin in an amount of 1 to 100 parts by weight per 100 parts by weight of the silica-based particles. Composition.   3. The aluminum compound-containing silicate particles are contained in an amount of 0.01 to 10 parts by weight and the non-halogen flame retardant is contained in an amount of 5 to 200 parts by weight per 100 parts by weight of the olefin polymer. The olefin polymer composition described in 1.   The olefin polymer composition according to any one of claims 1 to 3, wherein the non-halogen flame retardant is magnesium hydroxide.

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