JP3173769B2 - Method for producing flame-retardant silane cross-linked polyolefin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a silane cross-linking of a flame-retardant polyolefin containing a silanol condensation catalyst and a flame retardant in one step by a carrier polymer containing a high concentration of an organic unsaturated silane or the like. To a silane crosslinking method for producing

[0002]

2. Description of the Related Art In order to impart flame retardancy to a polyolefin composition which has been widely used in coatings of electric wires and cables, hoses, sheets, and injection products, a halogen compound and antimony trioxide are added to the polyolefin. This has been achieved by the addition. However, these compositions are halogen compositions, and generate halogen-based gas upon combustion,
In addition, it is not preferable because the metal is corroded. In addition, the amount of smoke produced was large, visibility was poor, and evacuation and extinguishing activities in the event of a fire were severely restricted. In particular, recently, it has been strongly demanded not to generate such a halogen-based gas from the viewpoint of safety. Based on this situation,
Attention has been paid to inorganic flame retardants using hydrated metal compounds with extremely low smoke and harmfulness. In order to impart flame retardancy, resin composites containing magnesium hydroxide, aluminum hydroxide, and the like have been put to practical use. However, in these flame retardant resin compositions, generation of halogen-based gas can be prevented. In addition, there is a problem that a so-called drip phenomenon occurs in which the resin composition melts and drops during combustion, or the shape retention at high temperatures is poor.

[0003] In order to improve this, in addition to flame retardancy, in order to improve heat resistance, there is a method of crosslinking, for example, Japanese Patent Publication No. 57-24373, Japanese Patent Publication No. 57-2662.
No. 0 publication. However, the method described here requires a large-scale crosslinking device such as chemical crosslinking or electron beam crosslinking, which increases the cost of the equipment itself, the subsequent operation and maintenance cost, etc., and further increases the cost of the composition. Was invited. Also, JP-A-60-101129 and JP-A-6-101129
In the case of a flame-retardant crosslinked composition characterized in that a flame retardant is added to a silane-grafted polyolefin resin to which silane has been grafted in advance and finally crosslinked, as seen in JP-A-147463. In order to prevent premature crosslinking when compounding and kneading the flame retardant with the grafted polyolefin resin, only silane-grafted polyolefin resin with suppressed crosslinking can be used, and as a result, the degree of crosslinking of the silane-grafted polyolefin resin cannot be increased. Heat resistance was insufficient. This method also involves at least two reaction steps. That is, a silane grafting reaction step and a silanol condensation reaction step. Therefore, at least two extrusion steps are required, and an economic problem as an end product cannot be avoided.

A one-step process includes a mono-seal method. However, this method requires a liquid addition device for injecting the organic unsaturated silane in a liquid state into the extruder, but has problems of slippage and poor measurement. Extruders also require expensive and special types with large L / D to uniformly disperse small amounts of additives.
Economic problems are inevitable. In addition, very high technology is also required for extrusion, and a flame-retardant type has not been commercialized. Further, as a one-step process, a silane crosslinking method in which silane is introduced into a solid carrier polymer is disclosed in
No. 167229. However, in this method, the solid carrier polymer is a porous polymer or EVA, and additives such as a silanol condensation catalyst and an antioxidant are introduced into the solid carrier polymer in addition to the silane and the free radical generator. For this reason, there has been a problem that crosslinking efficiency and storage stability are inferior due to oligomerization by silane condensation or crosslinking inhibition by radical scavenging.
Here, no description is given of the flame-retardant type.

[0005]

DISCLOSURE OF THE INVENTION The present invention has solved these problems. In the silane crosslinking of a flame-retardant polyolefin containing a silanol condensation catalyst and a flame retardant, an organic unsaturated silane or the like is contained at a high concentration. An object of the present invention is to provide a silane cross-linking method for producing a flame-retardant silane cross-linked polyolefin in one step using a carrier polymer.

[0006]

According to the present invention, there are provided (i) a flame retardant of 50 to 20 with respect to 100 parts by weight of an α-olefin homopolymer or copolymer having a density of 0.92 g / cm ³ or less.
0 parts by weight, a flame-retardant polyolefin obtained by adding 0.5 to 10 parts by weight of a water absorbing agent and a silanol condensation catalyst, and (ii) d.
Tylene-ethyl acrylate copolymer (EEA), ethyl
Len-methyl methacrylate copolymer (EMMA), low
Polymer broth comprising at least one vinyl aromatic compound
And a weight consisting of at least one conjugated diene compound.
By hydrogenating a block copolymer consisting of united blocks
From the resulting hydrogenated block copolymers and their mixtures
A polymer selected from the group consisting of the general formula RR'Si
Y ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, and R ′ is a monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon or the same as Y) The organic unsaturated silane and a substantially water-free carrier polymer containing a free radical generator at a temperature higher than the crystal melting point of the base polymer of the flame-retardant polyolefin, and then react with the water. And producing a flame-retardant silane-crosslinked polyolefin. More preferably, the homopolymer or copolymer of α-olefin is a homopolymer of α-olefin such as ethylene or propylene, or a crystalline block or random copolymer of α-olefin and another α-olefin. Copolymers or copolymers of α-olefins with polar monomers such as vinyl acetate, maleic anhydride, acrylic acid, etc., and mixtures thereof, having a density of 0.
It is 92 g / cm ³ or less . Key is added the amount of 1-5 wt% of catcher rear polymers, one or more silane coupling agents flame retardants, silicone derivatives, a surface-treated magnesium hydroxide or aluminum hydroxide with a fatty acid or fatty acid metal salt, water-absorbing agent Is a method for producing a flame-retardant silane cross-linked polyolefin, which is surface-treated with one or more silane coupling agents, silicone derivatives, fatty acids or fatty acid metal salts and has a mean particle size of 1 to 5 μm.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The α-olefin homopolymer or copolymer used in the present invention may be a homopolymer of α-olefin such as ethylene or propylene, or a crystalline block or random copolymer of α-olefin and another α-olefin. Polymers such as crystalline propylene-ethylene block copolymer, ethylene-butene-1 random copolymer, propylene-butene-1 random copolymer, or α-olefin, vinyl acetate, maleic anhydride And copolymers with polar monomers such as acrylic acid (including graft copolymers)
And a mixture of these having a density of 0.92 g / cm
³ or less. When the density exceeds 0.92 g / cm ³ , the solubility of the flame retardant in the homopolymer or copolymer of the α-olefin becomes poor, and the flame retardancy decreases.

The flame retardant used in the present invention has a decomposition initiation temperature in the range of 150 to 450 ° C. and a general formula
A compound represented by MmOn · XH ₂ O (where M is a metal, m and n are integers of 1 or more determined by the valency of the metal, and X is a number indicating the water of crystallization) or a double salt containing the compound. Specifically, aluminum hydroxide (Al ₂ O ₃ .3H ₂ O; or Al
(OH) ₃ ), magnesium hydroxide (MgO · H ₂ O; or Mg (O
H) ₂ ), calcium hydroxide (CaO · H ₂ O; or Ca (O
H) ₂ ), barium hydroxide (BaO.H ₂ O; or BaO.9H
₂ O), zirconium oxide hydrate (ZrO · nH ₂ 0), tin oxide hydrate (SnO · H ₂ 0), basic magnesium carbonate (3MgC
O ₃ · Mg (OH) ₂ · 3H ₂ O), hydrotalcite (6MgO · Al ₂
O ₃ .H ₂ O), dawsonite (Na ₂ CO ₃ .Al ₂ O ₃ .nH ₂ O), borax (Na ₂ O.B ₂ O ₅ .5H ₂ O), and other zinc borate and metaboric acid Zinc, barium metaborate, zinc carbonate, magnesium-calcium carbonate, calcium carbonate, barium carbonate,
Molybdenum oxide, red phosphorus, triethyl phosphate, tricresyl phosphate, triphenyl phosphate, cresyl phenyl phosphate, octyl diphenyl phosphate, diethylene phosphate ethyl ester, dihydroxypropylene phosphate butyl ester, ethylene disodium phosphate, Examples thereof include ammonium polyphosphate, melamine phosphate, and guanidine phosphate, and these may be used alone or in combination of two or more, and are preferably magnesium hydroxide and aluminum hydroxide. The flame retardant preferably has been subjected to a surface treatment with a silane coupling agent, a silicone derivative, a fatty acid, a fatty acid metal salt, or the like. (i) The silane coupling agent has a reactive group (a methoxy group, an ethoxy group, a carboxyl group, a cellosolve group, or the like) that reacts with an inorganic substance at one end of the molecule, and is generally a trifunctional group. Often have a group,
Of course, it may be bifunctional or monofunctional. The other end has a reactive group (vinyl group, epoxy group, methacryl group, amino group, mercapto group, etc.) that chemically bonds to the resin side as an organic material, and the main chain has an alkoxy oligomer as a skeleton. Things. (ii) As the silicone derivative, a type in which a part of the methyl group of dimethylpolysiloxane is substituted with various organic groups, and as the various modified organic groups, α-methylstyrene group,
modifying groups for improving compatibility, hydrophilicity, lubricity, water repellency, etc. of α-olefin groups, polyether groups, alcohol groups, fluoroalkyl groups, etc., amino groups, mercapto groups, epoxy groups, carboxyl groups A wide variety of modified group derivatives, such as a modified group for the purpose of reactivity and hygroscopicity of a group or the like, a releasing group for substitution of a higher fatty acid, carnauba, or amide, and a modified group for the purpose of polishing, may be mentioned.

(Iii) Fatty acids include saturated and unsaturated fatty acids, and include fatty acids having 6 to 22 carbon atoms, and particularly include _C18 stearic acid and oleic acid. (iV) The metal salt of a fatty acid refers to a metal soap in which the above fatty acid is bonded to a metal, and particularly includes sodium stearate, potassium stearate, sodium oleate, potassium oleate, and the like. Of course, fatty acids having a side chain bonded to a metal, regardless of whether they are straight-chain saturated or unsaturated, are also effective. When the flame retardant surface-treated by (i) to (iV) or a mixture thereof is blended from 50 parts by weight to 200 parts by weight, when it is compatible with or reacts with a low-density low-crystalline polymer and is filled at a high level However, a composition excellent in low-temperature properties, flexibility and processability can be easily formed. However, when the composition is less than 50 parts by weight, the flame retardant effect is significantly reduced.
If it exceeds 200 parts by weight, the flame retardancy is remarkably improved, but the mechanical properties such as flexibility and low-temperature properties are reduced, and the workability is extremely deteriorated.

The water-absorbing agent used in the present invention includes quick lime (calcium oxide), magnesium oxide, barium oxide, aluminum oxide, magnesium aluminum.
Oxides, magnesium aluminum hydroxide carbonate, silica gel, anhydrous calcium sulfate, anhydrous copper sulfate and the like, preferably quicklime. Those surface-treated by the above (i) to (iV) or a mixture thereof are preferable, and this water-absorbing agent is added to reduce the amount of water adhering to the flame-retardant polyolefin. This is because if there is moisture attached to the flame-retardant polyolefin, early crosslinking occurs in the silane crosslinking step. The amount of moisture adhering to cause this early crosslinking is about 100 ppm or more. In order to suppress the amount of moisture adhering to less than 100 ppm, the water absorbing agent must be 0.5 to 10 ppm.
Parts by weight must be added. If the amount is less than 0.5 part by weight, the amount of adhering water becomes 100 ppm or more, causing early crosslinking. Further, even if the amount exceeds 10 parts by weight, the effect of reducing the amount of adhering water is not further increased, and the mechanical properties may be deteriorated. In addition, a water absorbing agent having an average particle diameter of 1 to 5 μm is preferable in order to have excellent dispersibility in the flame-retardant polyolefin and to obtain a more uniform adsorbed moisture absorbing effect.

The silanol condensation catalyst of the present invention includes dibutyltin dilaurate, stannous acetate, dibutyltin diacetate, dibutyltin dioctoate, lead naphthenate, zinc caprylate, cobalt naphthenate, tetrabutyl titanate, and stearic acid. Organic metal compounds such as lead, zinc stearate, cadmium stearate, barium stearate, calcium stearate and the like can be mentioned. The amount of these additives is 0.01 to 0.1% by weight, preferably 0.03 to 0.07% by weight, based on the total weight of the flame-retardant silane crosslinked polyolefin. 0.01% by weight
If it is less than 0.1%, a sufficient crosslinking reaction does not proceed, while if it exceeds 0.1% by weight, crosslinking is locally advanced in the extruder at the time of extrusion, and the appearance is remarkably deteriorated. Also, the silanol condensation catalyst must be added to the flame-retardant polyolefin. This is because the addition of a carrier polymer impregnated with an organic unsaturated silane and a free radical generator promotes oligomerization by condensation of the silane and causes deterioration in appearance.

[0012] The organic unsaturated silane of the present invention is grafted onto the base resin so as to be a cross-linking point between the base resins. Examples of the organic unsaturated silane used in the present invention include a compound represented by the general formula RR'SiY ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, and R 'is an aliphatic unsaturated hydrocarbon group. A compound represented by a monovalent hydrocarbon group other than hydrogen or the same as Y) is used. It is desirable to use an organic unsaturated silane represented by the general formula RSiY _{3 in} which R ′ is the same as Y, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, allyltrimethoxysilane, allyltriethoxysilane. Examples include silane. The amount of these additives is from 0.1 to 2% by weight, preferably from 0.4 to 1% by weight, based on the total weight of the flame-retardant silane-crosslinked polyolefin.
It is. When the amount is less than 0.1% by weight, sufficient grafting does not occur. When the amount is more than 2% by weight, molding failure occurs and it is not economical.

[0013] The free radical generator of the present invention acts as an initiator of the silane grafting reaction. The free radical generator used in the present invention includes various organic peroxides and peresters having a strong polymerization initiating action, such as dicumyl peroxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, Di-t-butyl peroxide, t-butylcumyl peroxide, di-benzoyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylperoxypivalate, t -Butylperoxy-2-ethylhexanoate and the like. The addition amount of these is 0.01 to 0.1% by weight, preferably 0.02 to 0.0% by weight based on the total weight of the flame-retardant silane crosslinked polyolefin.
5% by weight. If the amount is less than 0.01% by weight, a sufficient silane grafting reaction does not proceed. If the amount exceeds 0.1% by weight, the extrudability decreases and the molding surface deteriorates.

By swelling the carrier polymer of the present invention with a liquid mixture in which a free radical generator is dissolved in silane, the free radical generator and silane can be added to the carrier polymer. At this time, the carrier polymer must be preheated to add a high concentration of silane, but the temperature must be lower than the crystal melting point so that the polymer does not melt. If the temperature is higher than the crystal melting point, the pellets are melted and workability is hindered. Also, the carrier polymer must be in particulate form and be solid compatible with the cross-linkable flame retardant polyolefin and silane. Compatible means that the carrier polymer must not readily react with the silane and must be dispersible or soluble in the flame retardant polyolefin. Suitable carrier polymers are non-hygroscopic. That is, it is preferred that the water absorption be relatively slow to minimize the potential for premature hydrolysis and condensation of the silane. In any event, the carrier polymer should be substantially free of water. The carrier polymer of the invention is usually in the form of granules or granules in the form of pellets, the preferred form being pellets.

[0015] As carrier polymer used in the present invention, et styrene - ethyl acrylate copolymer (EEA), ethylene - methyl methacrylate copolymer (EMMA), ethylene - vinyl acetate copolymer (EVA), ethylene - Propylene copolymer (EP
R), ethylene-propylene-diene copolymer (EPD)
M), a polymer block consisting of at least one vinyl aromatic compound, at least one conjugated diene compound
Ranaru polymer block consisting of a block copolymer hydrogenated block copolymer obtained by hydrogenating, for example, hydrogenated styrene - isoprene block copolymer (SEPS), hydrogenated styrene - butadiene block copolymer (SEBS )
And mixtures thereof.
The carrier polymer is added in an amount of 1 to 5% by weight based on the total weight of the flame-retardant silane cross-linked polyolefin. When the amount is less than 1% by weight, sufficient grafting does not occur, and when the amount exceeds 5% by weight, molding failure occurs and it is not economical. As other additives of the flame-retardant polyolefin, if necessary, additives usually used, for example, antioxidants, neutralizers, ultraviolet absorbers, antistatic agents, pigments,
A dispersant, a thickener, a metal deterioration inhibitor, a fungicide, a flow regulator, or the like, or another synthetic resin can be contained.
In the present invention, the silanol condensation catalyst was added to the base polymer.However, in order to improve the degree of dispersion of the silanol condensation catalyst, another carrier other than the above-described carrier polymer impregnated with the organic unsaturated silane and the free radical generator was used. A carrier polymer, for example, a polyolefin resin in which a silanol condensation catalyst is previously melt-mixed may be used. In this case, the base polymer and the two types of carrier polymers are charged into a molding machine such as an extruder at an appropriate mixing ratio.

[0016]

Embodiments will be described below with reference to embodiments. << Production of Flame-Retardant Polyolefin >> Each component was mixed according to the mixing ratio shown in Table 1 and the temperature was adjusted to 1 using a Banbury.
The mixture was kneaded at 60 to 180 ° C and granulated. << Production of Carrier Polymer >> According to the compounding ratio as shown in Table 2, the carrier polymer is first charged into a super mixer, mixed with stirring, and preheated to 80 ° C. Next, a liquid mixture in which a free radical generator was dissolved in an unsaturated silane was charged into a supermixer, and the carrier polymer was impregnated with stirring for 10 minutes.

The raw materials used are as follows. (1) D9052: Copolymer of ethylene and α-olefin / Soft Rex D9052 (manufactured by Nippon Petrochemical Co., Ltd.) Density; 0.905 g / cm ³ (2) P-0480: Copolymer of ethylene and α-olefin / Tuffmer P-0480 (manufactured by Mitsui Petrochemical Co., Ltd.) Density; 0.87 g / cm ³ (3) Magnesium hydroxide: Kisuma 5B (Kyowa Chemical Co., Ltd.)
(4) quicklime (1): average particle size 3 μm, stearic acid treated product (5) quicklime (2): average particle size 10 μm, stearic acid treated product (6) DBTDL: dibutyltin dilaurate (7) ) Antioxidant: phenolic antioxidant / Irganox 1010 (manufactured by Ciba Geigy) (8) Lubricant: low molecular weight polyethylene / sun wax 171
P (manufactured by Sanyo Chemical Industries, Ltd.) (9) EEA: Ethylene-ethyl acrylate copolymer (E
(A content: 23% by weight, crystal melting point: 93 ° C) (10) SEPS: hydrogenated styrene-isoprene block copolymer (styrene content: 30% by weight, crystal melting point: 135 ° C) (11) L-LDPE: linear low Density polyethylene (density;
0.924 g / cm ³ , MI: 3.0 g / 10 min) (12) VTMOS: vinyltrimethoxysilane (13) DCP: dicumyl peroxide

The evaluation method is as follows. (14) Water content (ppm): Karl Fischer method (150
(゜ C, 30 minutes) (15) Silane impregnating property: The impregnating property when the VTMOS / DCP liquid mixture was heated and stirred with a super mixer was evaluated. ○: Good impregnation, ×: Impregnable (16) Tape extrusion appearance: 50mmφ extruder 120-150-170-180-170 ℃ L / D: 20 Compression ratio 3.5 Tape die: width 100mm Lip interval 1mmt Evaluation: ○> The order of △> × was set, and the level of ○ was judged as acceptable. (17) Oxygen index: according to JIS K 7201. (18) Gel fraction (%): 120 ° C., 20 hours, xylene immersion method (19) Tensile strength (MPa) and elongation (%): JIS K 6760
by. (20) Hot set: According to IEC-540A. ○: passed, ×: failed

The obtained flame-retardant polyolefin and the carrier polymer were mixed in the ratios shown in Tables 3 and 4, a tape was extruded using an extruder, and further subjected to a crosslinking treatment by immersion in warm water. Using this extruded tape, gel fraction,
Evaluation of tensile strength, elongation and hot setting was performed. or,
The extruded tape was pressed to evaluate the oxygen index.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

As is clear from Tables 3 and 4, Example 1
Nos. 4 to 4 have good extrudability and excellent crosslinking properties, mechanical properties, flame retardancy and heat resistance. On the other hand, all of the comparative examples are not balanced in terms of extrudability, crosslinking properties, mechanical properties, flame retardancy, heat resistance, and the like.

[0025]

According to the present invention, a flame-retardant silane-crosslinked polyolefin having excellent extrudability and excellent crosslinking properties, mechanical properties, flame retardancy and heat resistance can be obtained.

Claims (8)

(57) [Claims] (1) α- having a density of 0.92 g / cm ³ or less;
50 to 200 parts by weight of a flame retardant and 0.5 to 10 parts by weight of a water absorbing agent, based on 100 parts by weight of the olefin homopolymer or copolymer.
Parts by weight and a flame-retardant polyolefin obtained by adding a silanol condensation catalyst, and (ii) ethylene-ethyl acrylate.
Polymer (EEA), ethylene-methyl methacrylate
Polymer (EMMA), at least one vinyl aromatization
Polymer block consisting of a compound and at least one conjugate
Block consisting of a polymer block consisting of a diene compound
Hydrogenated block copolymer obtained by hydrogenating copolymer
And polymers selected from the group consisting of
On the other hand, a compound represented by the general formula RR′SiY ₂ (R is a monovalent olefinically unsaturated hydrocarbon group, Y is a hydrolyzable organic group, and R ′ is a monovalent hydrocarbon group other than an aliphatic unsaturated hydrocarbon or Y
The same as above) and melt-mixed with a substantially water-free carrier polymer containing an organic unsaturated silane represented by the formula (1) and a free radical generator at a temperature higher than the crystal melting point of the base polymer of the flame-retardant polyolefin. A method for producing a flame-retardant silane-crosslinked polyolefin, which is followed by contacting with water and crosslinking. 2. The α-olefin homopolymer or copolymer is a crystalline block or random copolymer of an α -olefin and another α-olefin, or an α-olefin.
A copolymer, and mixtures thereof with the polar monomer,
Method for producing a flame-retardant silane-crosslinked polyolefin according to claim 1, wherein the density thereof is of 0.92 g / cm ³ or less. 3. A method of producing a flame-retardant silane-crosslinked polyolefin according to claim 1 or 2, wherein the amount of carrier polymer is 1 to 5% by weight based on the total weight of the flame-retardant silane-crosslinked polyolefin . 4. A flame retardant one or more silane coupling agents, silicone derivatives, the production of flame-retardant silane-crosslinked polyolefin according to claim 1 or 2, wherein the being surface treated with a fatty acid or fatty acid metal salts Method. 5. The magnesium hydroxide flame retardant, according to claim 1, 2 or 4 production method of the flame-retardant silane-crosslinked polyolefin, wherein the at least one selected from aluminum hydroxide. 6. A water-absorbing agent is one or more silane coupling agents, silicone derivatives, according to claim 1, 2 or, characterized in that it is surface treated with a fatty acid or fatty acid metal salts
5. The method for producing a flame-retardant silane-crosslinked polyolefin according to 4 . 7. The method of claim 1, 2 average particle diameter of the water-absorbing agent is characterized in that it is a 1 to 5 [mu] m, 4 or 6 production method of the flame-retardant silane-crosslinked polyolefin according. 8. The method of claim 1, 2 water-absorbing agent is characterized in that the quick lime, 4, 6 or 7 production method of the flame-retardant silane-crosslinked polyolefin according.