JP4796445B2 - Flame retardant synthetic resin composition containing exfoliated layered double hydroxide - Google Patents

Description

  The present invention relates to a flame retardant synthetic resin composition containing an inorganic compound containing no halogen or phosphorus for flame retardancy.

  The flame retardant of the combustible plastic is made by adding a flame retardant. In recent years, attempts have been made to add layered double hydroxide (LDH) for flame retardance due to concerns about environmentally hazardous substances generated during incineration. The problem at this time is that the LDH must be uniformly dispersed in the plastic matrix.

Layered double hydroxides (LDH) of the general formula ^{_{[M 2+ 1-x M 3+ x}} (OH) 2 ] ^{x +} layered with anion exchange ability represented by ^{_{[A n- x / n · yH 2}} O ] A compound. The crystal structure is composed of a regular octahedral hydroxide layer (basic layer) in which a part of divalent metal ions is replaced by trivalent metal ions, and an intermediate layer composed of anions and interlayer water. The feature of LDH is that there are various combinations of types and ratios of metal ions in the basic layer and types of intermediate anions. Many types of LDH have been synthesized so far, and much research has been conducted on uptake by inorganic and organic anion intercalation.

In general, in LDH, the charge density of the base layer is large, and the electrostatic attraction between the base layer and the intermediate layer is strong. Therefore, the delamination phenomenon as seen in many clay minerals is unlikely to occur. Therefore, although there are few reports on LDH that easily peels in water, there is JP-A-2004-189671. Here, an aromatic aminocarboxylic acid, particularly p-aminobenzoic acid, is intercalated as an anion in the intermediate layer, whereby a dispersion liquid dispersed in a lower alcohol such as water or ethanol is obtained. It is reported that. This is explained as a result of expanding the distance of the base layer by intercalating aromatic aminocarboxylic acid ions as compared with LDH intercalating CO ₃ ^2- ions. However, this LDH peeling phenomenon is complete in ethanol, which is a good solvent for aromatic aminocarboxylic acids such as p-aminobenzoic acid, but is incomplete in water with low solubility.

  In JP-A-2005-89269 and JP-A-2005-238194, an LDH that peels off to a basic layer in water or some kind of polar organic solvent in which an amino acid ion or an amino acid ion and a carboxylate ion are intercalated in an intermediate layer. Disclosure. In order to uniformly disperse these LDHs in the plastic, it is necessary to wet mix the LDH and the plastic in a solvent in which they are peeled off to the basic layer, and then distill off the solvent.

Japanese Patent Laid-Open No. 2001-261927 discloses that LDH is produced by mixing carbonated LDH and p-hydroxybenzoic acid that also serves as an acid catalyst with a phenol resin raw material in the production stage of a phenol resin, and producing an initial condensate from this mixture. It is said that a flame retardant resin composition dispersed in a state in which the is peeled is obtained. This method is naturally not applicable to the resol type.
JP 2004-189671 A JP 2005-89269 A JP 2005-238194 A JP 2001-261927 A

In these prior arts, all LDHs blended for flame retardance contain a compound having a free carboxyl group in the intermediate layer. Recently, the inventors have found that LDHs in which acetic acid is intercalated in the form of Mg, Zn or Ce salts, not as free acids in the intermediate layer, are almost completely nanosized in water, or in low molecular weight alkanols or alkylene glycols. It was found that it peeled off to the base layer. For this reason, this LDH is an aqueous resin composition, for example, an aqueous solution of a water-soluble polymer such as polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, methylcellulose, CMC, hydroxypropylcellulose, starch, emulsion or dispersion. It can be peeled and dispersed in the water-soluble polymer composition, coated and used for flame retarding of paper, nonwoven fabric and the like. However, this method would not be able to disperse the polymer in the peeled state in order to make the polymer insoluble in the liquid from which the LDH can be peeled off, such as water and alcohols, flame retardant.
Further, it has been confirmed that the adhesion to a metal plate or the like is improved by adding the LDH to PVA or the like.

  The object of the present invention is to provide a flame retardant synthetic resin composition comprising LDH uniformly dispersed in a peeled state, which has been difficult or requires complicated steps.

In order to solve the above problems, the present invention provides:
Formula (I):
M (II) _1-x M (III) _x (OH) ₂ (I)
(Wherein M (II) is Mg, Zn or a mixture thereof, M (III) is Al, and x is 0.2 to 0.33), Flame retardant synthesis comprising a flame retardant effective amount of layered double hydroxide composed of Mg, Zn or Ce acetate intercalated in the interlayer of the layer and interlayer water and reversibly exfoliating in water A resin composition is provided.

  According to the present invention, the synthetic resin is a polycondensation type resin including a raw material from which the layered double hydroxide is peeled in the production thereof, and the layered double hydroxide is added to the raw material in the process of manufacturing the synthetic resin. It is characterized by being uniformly dispersed in the synthetic resin in a peeled state by being added.

  In one embodiment, the synthetic resin is a phenol resin or amino resin whose raw material is formaldehyde or a polymer thereof (paraformaldehyde).

  In another embodiment, the synthetic resin is polyethylene terephthalate (PET) whose raw material is ethylene glycol.

  In a further specific example, the layered double hydroxide is blended in an amount of 1 to 50% by weight based on the solid content of the synthetic resin.

LDH peeling in water
The LDH exfoliating in water of the present invention is produced according to a method similar to a reconstruction method for the production of anion-intercalated LDH starting from carbonated LDH and a polyvalent metal salt of acetic acid to be intercalated can do.

  Reconstruction method is a method in which carbonated LDH is calcined in advance at a temperature of 400 ° C to 800 ° C and the pyrolysis product from which most of carbonate ions have been removed is reacted with other anions in water to produce reconstructed LDH. It is a method to make it. In the present invention, a thermal decomposition product of carbonate type LDH and a polyvalent metal acetate selected from Mg, Zn or Ce are reacted in water.

The starting carbonate type LDH has the formula (II):
_{^{[M (II) 2+ 1-x}} M (III) 3+ x (OH) 2 ] _{[(CO 3) x / 2 ·} yH 2 O ]
M (II) is Mg, Zn or a mixture thereof, M (III) is Al, and x is a number from 0.2 to 0.33. These naturally exist as hydrotalcites and can be synthesized according to a known method. Some of the synthetic hydrotalcites are commercially available from, for example, Kyowa Chemical Industry Co., Ltd. (Tokyo, Japan).

The reaction can be carried out at room temperature with stirring by adding a thermal decomposition product of carbonate-type LDH to an aqueous solution of polyvalent metal acetate. The ratio of the polyvalent metal acetate to the pyrolyzate of carbonate type LDH is at least equimolar to the Al content in the pyrolyzate in terms of Al ₂ O ₃ . In general, the reaction product is in the form of a gel. This gel is separated from the reaction mixture by filtration, centrifugation, etc., dried at a temperature of 60 ° C. or higher, and pulverized to obtain the LDH of the present invention. Compared to the X-ray diffraction pattern of the LDH in which the sodium carbonate was used for reconstruction instead of the carbonate type LDH and polyvalent metal acetate, the peak was shifted to the lower angle side. This suggests that the distance between the basic layers has increased. In addition, the infrared absorption spectrum of LDH of the present invention is characterized by no absorption near 1360 to 1390 cm ⁻¹ derived from the carboxyl group of the IR spectrum of LDH using sodium acetate in the reconstruction, and is characterized by 1390 to 1430 cm ⁻¹ . A typical peak is seen. This suggests that the polyvalent metal salt incorporated by reconstruction is chemically bonded to the base layer in a manner different from LDH reconstructed using sodium acetate. However, this binding mode has not yet been elucidated.

  The LDH of the present invention, unlike LDH intercalated with known aromatic amino carboxylic acids, is substantially completely delaminated in water to form a viscous colloidal solution or sol. This means that when the LDH (dried product) of the present invention is hydrated (wet) with different amounts of water and X-ray diffraction analysis is performed in this state, the peak gradually moves to the lower angle side as the amount of water increases. This is proved by the disappearance of this peak. The movement of this peak to the lower angle side indicates that water molecules enter the intermediate layer, gradually increasing the interlayer distance between the basic layers, and finally destroying the crystal structure. However, when LDH that has lost its crystal structure due to hydration and exfoliation is completely dried, it regains the same X-ray diffraction pattern as the original dry LDH, indicating that exfoliation is reversible.

  The aqueous dispersion of LDH of the present invention shows a much higher transmittance for visible light than the aqueous dispersion of carbonated LDH of the same concentration. This is because LDH is dispersed as smaller nano-sized particles as a result of peeling.

Matrix Synthetic Resin A first typical example of the matrix synthetic resin used in the present invention is a phenol resin. As is well known, a phenol resin (phenol-formaldehyde resin) is an addition polycondensation reaction product of a phenol compound such as phenol or cresol and formaldehyde. The history of phenolic resin has been around since 1907, and its manufacturing method has been established. A well-known manufacturing method is employed except that the LDH of the present invention is added to a mixture of a phenolic compound, formaldehyde or a polymer thereof and a catalyst (acid in the case of novolak, base in the case of resole) before heating. The generated oligomer (initial condensate) contains LDH dispersed in a peeled state at this time, and this is used for impregnation of a prepreg for manufacturing a printed wiring board, or for manufacturing a compound for compression molding. Can do.

  A second typical example of the matrix resin is an addition polycondensation product of amino compounds such as urea, melamine, dicyandiamide and the like, which are collectively called amino resins, and formaldehyde. In the case of an amino resin as well as a phenol resin, a resin composition in which LDH is dispersed in a peeled state can be produced by mixing the LDH of the present invention into the raw material mixture before the heating reaction.

  A further typical example of a matrix resin is polyethylene terephthalate (PET) resin. PET synthesizes terephthalic acid di (hydroxyethyl) ester from terephthalic acid or dimethyl terephthalate and excess ethylene glycol, which is transesterified in the presence of a catalyst in the molten state, and the resulting ethylene glycol is produced under vacuum. By distilling off, it is produced as a high molecular weight polymer. A composition containing LDH dispersed in a peeled state can be obtained by previously adding and mixing the LDH of the present invention with ethylene glycol.

Resin Composition The blending amount of LDH of the present invention can vary greatly depending on the type of matrix resin, the use of the resin composition, and the required flame retardancy, but generally ranges from 1 to 50% by weight with respect to the resin solids Is within. However, the optimum amount should be determined taking into account the particular resin, the application of the composition and the other physical properties required.

  As inorganic flame retardants for plastics, antimony trioxide, hydrated aluminum oxide and the like are generally used. These decrease the original physical properties of the resin, particularly the mechanical strength, in inverse proportion to the blending amount. When the LDH of the present invention is appropriately blended, a reinforcing effect that rather improves the strength of the resin, particularly the bending strength, is recognized. At this time, the film of the composition retains the gas barrier effect. Accordingly, when not only flame retardancy but also a reinforcing effect and / or gas barrier properties are desired at the same time, the optimum blending amount is 20% by weight or less, particularly 5 to 10% by weight with respect to the resin solid content. Will.

  The following examples are provided for the purpose of illustrating the invention and are not intended to be limiting. In the examples, “parts” and “%” are based on weight unless otherwise specified.

Part I Production of LDH exfoliating in water Example I-1
Mg-Al carbonate type LDH (DHT-6 manufactured by Kyowa Chemical Industry Co., Ltd.) was heated at 700 ° C. for 20 hours to obtain a thermal decomposition product. After adding 96.3 g of this pyrolyzate to 1 L of magnesium acetate tetrahydrate 0.28 mol / L (60 g / L) aqueous solution and stirring at room temperature for 15 hours, the produced solid (gel) was separated by filtration, It was dried at 90 ° C. for 10 hours, and pulverized to obtain a reconstructed LDH. This is called LDH I-1.

Example I-2
The operation of Example I-1 was repeated to obtain LDH I-2 except that the magnesium acetate aqueous solution was changed to a cerium acetate monohydrate 0.28 mol / L (94 g / L) aqueous solution.

Example I-3
The operation of Example I-1 was repeated except that the magnesium acetate aqueous solution was changed to a zinc acetate dihydrate 0.28 mol / L (61.5 g / L) aqueous solution to obtain LDH I-3.

Example I-4
To ₂ L of 1 mol / L aqueous solution of Na ₂ CO ₃ , 2.6 L of 1 mol / L aqueous solution of ZnCl ₂ and 1.4 L of 1 mol / L aqueous solution of AlCl ₃ were dropped while maintaining the pH of the reaction solution at 7. Aging was performed at 40 ° C. for 1 hour. After removing chloride ions from the reaction mixture by decantation, ₂ L of Na ₂ CO ₃ 1 mol / L aqueous solution was added and heated to reflux for 5 hours. The solid product was separated by filtration, washed with water, dried under reduced pressure at 60 ° C. for 24 hours, and pulverized to obtain a Zn—Al carbonate type LDH.
Next, this Zn—Al carbonate type LDH was heated at 450 ° C. for 20 hours to obtain a thermal decomposition product. After adding 115.1 g of this thermal decomposition product to 1 L of zinc acetate 0.28 mol / L (61.5 g / L) aqueous solution and stirring at room temperature for 15 hours, the reaction mixture containing the solid was evaporated to dryness at 100 ° C. and pulverized. did. The resulting product is called LDH I-4.

Example I-5
Mg-Zn-Al carbonate type LDH (Alkamizer manufactured by Kyowa Chemical Industry Co., Ltd.) was heated at 700 ° C. for 20 hours to obtain a thermal decomposition product. 65.3 g of this pyrolyzate was added to 1 L of an aqueous solution of magnesium acetate tetrahydrate 0.14 mol / L (30.0 g / L) and stirred at room temperature for 48 hours, and then the resulting solid (gel) was separated by filtration. And dried at 90 ° C. for 10 hours and pulverized to produce LDH I-5.

  In all of the following parts II and III, LDH-1 produced in Example I-1 was used.

Part II Phenol resin in which exfoliated LDH was dispersed Experimental Example 1 Blank 100 g of phenol and 157 g of 37% formaldehyde were mixed, 5.0 g of 10% sodium hydroxide was added thereto, and the mixture was stirred and mixed at 70 ° C. for 2 hours. Thereafter, atmospheric pressure dehydration and vacuum dehydration were performed to obtain phenol resin A.

Experimental Example 2 Comparative Example 100 g of phenol and 157 g of 37% formaldehyde were mixed, and DHT-6 (6.94 g) manufactured by Kyowa Chemical Industry Co., Ltd. and 5.0 g of 10% sodium hydroxide were further added thereto, followed by stirring and mixing at 70 ° C. for 2 hours. Thereafter, atmospheric pressure dehydration and vacuum dehydration were performed to obtain phenol resin B.

Experimental Example 3 Invention 157 g of 37% formaldehyde was mixed and stirred with 6.94 g of peelable double hydroxide, and after layer peeling, 100 g of phenol was added and stirred and mixed at 70 ° C. for 2 hours, followed by atmospheric pressure dehydration and vacuum dehydration. The phenol resin C was obtained.

Preparation of strength test sample of phenol resin The phenol resins A to C prepared in Experimental Examples 1 to 3 are respectively placed in a mold for preparing a strength test sample and pressed at 190 ° C. for 20 minutes to obtain 6.4 × 13. 4 * 108.8 mm test pieces A to C were obtained.

Preparation of gas permeability test sample Phenol resins A and C prepared in Experimental Examples 1 and 3 were each placed in a gas permeability test sample preparation mold and pressed at 190 ° C. for 20 minutes to obtain a thickness of 0.3 mm, Test pieces D and E having a diameter of 100 mm were obtained.
The phenol resin B (comparative example) was distorted, and a measurable test piece could not be prepared.
Test piece A, D: Resin only Test piece B: Comparative test piece C, E: The present invention

The bending strength test was performed using the bending strength test specimens A to C. For the test, an autograph AG-IS manufactured by Shimadzu Corporation was used. See Table 1 below for results.

Measurement of deflection temperature under load The deflection temperature under load was measured using test pieces A to C. For the test, HEAT DISTORTION TESTER HD-500 manufactured by Yasuda Seiki Co., Ltd. was used. See Table 2 for results below.

Measurement of oxygen index Using the test pieces A to C, the oxygen index was measured. For the test, a flammability tester ON METER (ON-1M type) manufactured by Suga Test Instruments Co., Ltd. was used. See Table 3 for the results below.

A gas permeability test (based on JIS K7126 B method) was performed using the gas permeability test specimens D and E.
In the test, OXTRAN 10 / 50A manufactured by MOCON was used. See Table 4 below for results.

Part III PET resin in which peeled LDH was dispersed. Experimental Example 4 Blank 45 mL (2.3 mol) of dimethyl terephthalate and 320.3 g (5.16 mol) of ethylene glycol were used in three 1 L capacities. Place in a neck flask, add 0.2 g of antimony oxide and calcium acetate, raise the liquid temperature to 220 ° C., distill off the methanol produced by the reaction, and then add 0.5 g of 50% phosphoric acid again. After heating, the temperature of the liquid reached 260 ° C., the inside of the tank was evacuated, and the ethylene glycol formed by the polymerization reaction was removed to obtain polyethylene terephthalate resin A.

Experimental Example 5 Comparative Example 45 mL of dimethyl terephthalate and 326.8 g of ethylene glycol mixed with 6.5 g of carbonate-type double hydroxide (DHT-6 manufactured by Kyowa Chemical Industry Co., Ltd.) Put in a neck flask, add 0.2 g of antimony oxide and calcium acetate, raise the liquid temperature to 220 ° C., distill off the methanol produced by the reaction, then add 0.5 g of 50% phosphoric acid and heat again. After the liquid temperature reached 260 ° C., the inside of the tank was evacuated to remove unnecessary ethylene glycol formed by a polymerization reaction, to obtain a polyethylene terephthalate resin B.

Experimental Example 6 The present invention 450.0 g of dimethyl terephthalate and 326.8 g of ethylene glycol to which 6.5 g of peelable double hydroxide was added and mixed in advance were placed in a 1 L three-necked flask, and antimony oxide 0 was added thereto. .2g and calcium acetate were added, the liquid temperature was raised to 220 ° C, methanol produced by the reaction was distilled, 0.5g of 50% phosphoric acid was added, and then heated again, and the liquid temperature reached 260 ° C. A polyethylene terephthalate resin C was obtained by removing the unnecessary ethylene glycol formed by the polymerization reaction in a vacuum state in the rear tank.

Preparation of polyethylene terephthalate resin strength test sample Polyethylene terephthalate resins A to C prepared in Experimental Examples 4 to 6 were put in three-necked flasks each having a capacity of 300 ml, heated to 260 ° C., and then used as a phenol resin. The test piece F, G, and H was obtained after pouring into the same strength test sample preparation metal mold | die and cooling at room temperature.
Test piece F: Blank test piece G: Comparative example test piece H: The present invention

Measurement of oxygen index The oxygen index was measured using test pieces F, G, and H, respectively. For the test, a flammability tester ON METER (ON-1M type) manufactured by Suga Test Instruments Co., Ltd. was used. See the table below for results.

The bending strength test was performed using the bending strength test specimens F, G, and H. For the test, an autograph AGS500B manufactured by Shimadzu Corporation was used. See Table 6 below for results.

Claims (4)

Formula (I):
M (II) _1-x M (III) _x (OH) ₂ (I)
(Wherein M (II) is Mg, Zn or a mixture thereof, M (III) is Al, and x is 0.2 to 0.33), Flame retardancy comprising an intercalated Mg, Zn or Ce acetate and interlayer water in the middle layer of the layer and containing a flame retardant effective amount of layered double hydroxide that reversibly peels off in water A synthetic resin composition, wherein the synthetic resin is a polycondensation-type resin containing a raw material from which the layered double hydroxide is peeled off during the production thereof, and the layered double hydroxide is produced in the process of producing the synthetic resin. A flame-retardant synthetic resin composition, which is uniformly dispersed in the synthetic resin in a peeled state by being added to a raw material.   The flame retardant synthetic resin composition according to claim 1, wherein the synthetic resin is a phenol resin or an amino resin which is formaldehyde or a polymer thereof.   The flame-retardant synthetic resin composition according to claim 1, wherein the synthetic resin is polyethylene terephthalate whose raw material is ethylene glycol.   The flame retardant synthetic resin composition according to any one of claims 1 to 3, wherein the layered composite hydroxide is blended in an amount of 1 to 50% by weight based on the solid content of the synthetic resin.