WO2007051377A1 - Hydrotalcite laminated by organic anion(s) comprising a double bond and its use as a heat stabilizer - Google Patents

Abstract

A hydrotalcite laminated by organic anion(s) comprising a double bond, which has the following formula: [M2+1 xM3+X(OH)2]An-x/n·mH2O-, wherein An- is an organic anion(s) comprising a double bond selected from maleate, acrylate, or vinylacetate. Because the double bond contained in the hydrotalcite can react with the conjugated double bonds produced by the decomposition of PVC, the hydrotalcite of the invention can remarkably improve the long term heat stability of PVC. According the result of the static thermal aging rest performed on PVC incorporated therein the hydrotalcite, calcium stearate, and zinc stearate, it is shown that the hydrotalcite can increase the heat stability of PVC significantly and hence is an excellent PVC heat stabilizer.

Description

 Double-bonded organic anion intercalated hydrotalcite and used as a heat stabilizer

Technical field

 The present invention relates to a novel supramolecular intercalated hydrotalcite, in particular to a double bond organic anion intercalated hydrotalcite, and the hydrotalcite as a composite heat stabilizer for PVC. Background technique

 PVC and other chlorine-containing polymers can undergo auto-catalytic reaction of de-HC1 under high temperature or under the influence of high-energy rays (such as ultraviolet rays). The thermal decomposition mechanism is generally considered to be of three types: (1) Freedom in an oxygen-containing environment Base mechanism; (2) Ion mechanism in a nitrogen atmosphere; (3) Single molecule mechanism under vacuum conditions. The thermal degradation of PVC is a very complicated process. The direct consequence of degradation is that the color becomes darker and the structure and properties of the product are greatly damaged. Heat stabilizers are one of the main additives that are indispensable for the processing of PVC and other chlorine-containing polymers.

 According to the thermal decomposition mechanism of PVC, the heat stabilizer should have the following functions: 1. It can absorb and neutralize the HC1 released by PVC during the process, preventing its autocatalysis in the presence of oxygen, and generating non-ionic products; 2. It can stop the growth of unsaturated silent bonds by means of addition, reduction, oxidation or free radical reaction; 3. It has light stabilizing effect, can absorb and reflect ultraviolet rays, such as light shielding agent, ultraviolet absorber, quencher, Free radical trapping agent and other substances; 4, with PVC has good solubility, easy to manufacture transparent products; 5, should be colorless, odorless, non-toxic, non-migratory, moderate price, does not affect the rheology of PVC resin and its basic feature.

 At present, thermal stabilizers can be mainly classified into salt-based lead salts, metal soaps, organotins, rare earths and composite stabilizers according to their chemical structures. With the increasing awareness of environmental protection, PVC heat stabilizers are developing towards low toxicity, pollution-free and high efficiency. It is of great significance to develop and develop a new generation of environmentally-friendly PVC heat stabilizers.

Hydrotalcite, also known as Layered Double Hydroxides (LDHs), is a typical anionic layered compound whose interlayer anion can be inorganic Ions, organic anions, complex anions, homopoly and heteropoly anions or layered compounds. Because the surface of the laminate is alkaline, it can absorb the HC1 and other chlorinated high polymers, which can explain the effect of autocatalytic decomposition. In addition, due to the exchangeability of ions between the hydrotalcite layers, Interlayer C0 ₃ ² - can be exchanged with HC1 entering the layer to achieve absorption of HC1, stable PVC and other chlorine-containing polymers.

 Literature [1]: In the monograph of Vicente Rives [Layered Double Hydroxides: Present and Future, New York, Nova Science Publishers, Inc., 2001], a variety of organic anion intercalated hydrotalcites, such as p-benzoquinone, have been discovered. Acid, adipic acid, succinate, dodecylsulfonate, p-hydroxybenzoate, benzoate, etc., may be prepared by ion exchange, coprecipitation, and the like. The organic anion intercalation structure hydrotalcite containing double bonds has not been reported in the literature.

Document [2]: US Patent United States Patent 4299759 (1981) reported that Japan's Kyowa Chemical Company took the lead in 1980 to meet the following general formula: M _gl . _x Al _x (OH) ₂ A _x/n ⁿ - · mH ₂ 0 Hydrotalcite (0<x < 0.5) (A ⁿ - is C0 ₃ ² —) is filled into PVC for use as a heat stabilizer, and the result is a significant increase in the thermal stability of PVC. When _{7 Alo.3 (OH) 2 (C0} 3) o.i5 · 0.55H 2 O, 0.75 parts of zinc stearate and 0.3 parts of an organotin, 180 ° C condition was added 1 part Mg ₀ 100 parts of PVC. The thermal stabilization time of PVC can be extended to 62 minutes. Two parts of stearic acid/zinc stearate heat stabilizer were used under the same conditions, and the heat stabilization time was only 38 minutes. Up to now, the hydrotalcite applied to the PVC heat stabilizer has been limited to the type of co ₃ ² - between the layers, and the chemical composition of the hydrotalcite laminate and the anion species of the interlayer are not fully utilized. Therefore, the cations of the laminate and the interlayer anions are modulated, and the elements which are beneficial to improve the thermal stability of the PVC are added, and a novel structure of the supramolecular intercalated hydrotalcite having a better thermal stability to PVC can be formed.

Literature [3]: Lu Shiguang's "Handbook of Plastics Additives" (Beijing, Light Industry Press, 1986) describes the use of unsaturated materials containing double bonds as heat stabilizers, because it can be shared with PVC molecules. The conjugated double bond undergoes a diene addition reaction, thereby destroying the conjugated structure, inhibiting discoloration, and improving the thermal stability of the PVC. Due to their poor thermal stability, these materials decompose under higher temperature conditions and are often used as auxiliary heat stabilizers or as an aid to heat stabilizers. Group. For example, maleic acid emits toxic irritating gases when heated and is often used as a group in organotin heat stabilizers. Since the hydrotalcite has a layered structure, the laminate can protect the organic substances entering the interlayer, thereby greatly improving the thermal stability of the interlayer anions and expanding the application range thereof. Summary of the invention

 SUMMARY OF THE INVENTION An object of the present invention is to provide an organic anion intercalated hydrotalcite containing a double bond; another object of the present invention is to use the hydrotalcite as a PVC heat stabilizer.

 The double bond organic anion intercalated hydrotalcite provided by the invention has the chemical composition formula:

[Μ ²⁺ ₁ -χ Μ ³⁺ _χ (ΟΗ) ₂ ]Α ^η · _χ/η · m3⁄40,

Wherein M ²⁺ represents one or both of divalent metal cations Mg ²⁺ , Zn ²⁺ , Ca ²⁺ , Cu ² Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cd ²⁺ Preferred as one or both of Mg ²⁺ , Zn ²⁺ , and Ca ²⁺ ;

M ³⁺ represents one of a trivalent metal cation Al ³⁺ , Ni ³⁺ , Co ³⁺ , Fe ³⁺ , Mn ³⁺ , Cr ³⁺ , V ³⁺ , Ti ³⁺ , preferably Al ^{3 +} or Ni ³⁺ ;

Α ^η · is one of a double bond organic anion maleate, acrylate, butenoate, aminobutenoate, oleate, linoleate, linolenate, preferably maleate, acrylate or Butenoate

X is the mole fraction of M ³⁺ ions, and its value ranges from 0.2 < x 0.33 ;

 m is the amount of crystal water, and its value ranges from 0 m < 2.

 It should be noted that the subscripts of the elements or groups in the composition formula (chemical formula) of the hydrotalcite in the present invention are approximate values obtained in the calculation process.

 The preparation method of the organic-organic intercalated hydrotalcite containing the silent bond according to the present invention is as follows:

A. Dissolving M ²⁺ soluble nitrate and M ³⁺ soluble nitrate in a molar ratio of M ²⁺ /M ^{3+ of} about 2 ~ 4 in deionized water de C0 ₂ to form a mixed salt solution , the concentration of M ²⁺ is 0.1 ~ 1.6mol / L; the ratio of the number of moles of NaOH to the total number of moles of metal ions in the mixed solution a ratio of about 1.8 to 2.5, dissolving NaOH in deionized water de C0 ₂ to prepare an equal volume of alkali solution with the mixed salt solution; adding the above two solutions to the reactor at the same time, reacting at room temperature for about 0.5-6 min, The obtained slurry is crystallized under the protection of N ₂ at 60 to 100 ° C for about 3 to 8 hours, filtered, and washed with deco ₂ deionized water to obtain a nitrate-type hydrotalcite precursor filter cake;

 B. Dissolving a double-bond organic acid in ethylene glycol to prepare a solution having an organic acid content of about 10 to 50% by mass, and dispersing the nitrate-type hydrotalcite precursor prepared in step A in ethylene glycol. The preparation of the hydrotalcite precursor has a mass percentage of 10% to 70%, and the ethylene glycol solution containing the organic acid is in a ratio of the organic acid to the hydrotalcite precursor in a molar ratio of about 1:1 to 5 The mixture is added dropwise to an ethylene glycol dispersion containing an aqueous talc precursor, and the reaction system is controlled to have a pH of 4.0, heated to a reflux temperature, and reacted for 0.5 to 6 hours. After washing and drying, an intercalated hydrotalcite is obtained.

In step A, M ²⁺ represents one of divalent metal cations Mg ²⁺ , Zn ²⁺ , Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cd ²⁺ Or two, preferably one or two of Mg ²⁺ , Zn ²⁺ , Ca ²⁺ ; M ³⁺ represents a trivalent metal cation Al ³⁺ , Ni ³⁺ , Co ³⁺ , Fe ³⁺ One of Mn ³⁺ , Cr ³⁺ , V ³⁺ , Ti ³⁺ , preferably Al ³⁺ or Ni ³⁺ ;

 The double bond-containing organic acid in the step B may be one of maleic acid, acrylic acid, crotonic acid, aminobutenoic acid, oleic acid, linoleic acid, and linolenic acid, preferably maleic acid or acrylic acid. Or butenoic acid.

 XR, IR and elemental analysis of the above products show that the guest functional molecules have been assembled into the layered material hydrotalcite layer and the double bonds in the molecule are well preserved, and the crystal crystal phase is single and the structure is consistent. Intercalation structure hydrotalcite material.

The double bond-containing organic anion intercalated hydrotalcite prepared above was mixed with calcium stearate and zinc stearate and added to PVC for static heat aging test. The results are shown in Table 1, indicating that the supramolecular insertion prepared by the present invention The layer structure hydrotalcite can effectively improve the thermal stability of PVC, and is an excellent PVC heat stabilizer. The reason is that the double bond in the molecule can react with the conjugated double bond generated by the decomposition of PVC to form a diene addition reaction, blocking the conjugate. The continuation of the double bond destroys the autocatalytic decomposition of PVC and can significantly improve the thermal stability of PVC. The present invention provides an organic anion intercalated hydrotalcite containing a double bond, which is used as a hydrotalcite

PVC heat stabilizer can significantly improve the thermal stability of PVC. DRAWINGS

 BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an XRD spectrum of a hydrotalcite precursor and a maleate intercalated hydrotalcite prepared in Example 1, wherein a is a curve of a hydrotalcite precursor and b is a curve of a maleate intercalated hydrotalcite.

 2 is an IR spectrum of a hydrotalcite precursor, maleic acid intercalated hydrotalcite, and maleic acid prepared in Example 2, wherein a is a curve of a hydrotalcite precursor, and b is a maleate intercalated hydrotalcite. The curve, c is the curve of maleic acid. '

 Figure 3 is a TG-DTA spectrum of the maleate intercalation MgZnAl-LDHs prepared in Example 2. detailed description

 Example 1:

Step Α· Dissolve 10.26 g Mg(N0 ₃ ) ₂ ■ 6H ₂ 0 and 7.50 g A1(N0 ₃ ) ₃ · 9H ₂ 0 in deionized water de C0 ₂ to prepare 50 ml mixed salt solution, dissolve 4.8 g NaOH A 50 ml alkali solution was prepared in deionized water de C0 ₂ . The two solutions were simultaneously added to the reactor for about 2 min, and recrystallized at 100 Torr for 6 hours under N ₂ protection, filtered, and washed with deionized water of CO ₂ to obtain 4.87 g of water of Mg: Al = 2:1. Talc precursor filter cake MgAl-N0 ₃ -LDHs.

Step B. Disperse the above hydrotalcite precursor filter cake in 20 ml of ethylene glycol, dissolve 2.32 g of maleic acid in 3.0 ml of ethylene glycol, control pH>4.0, and add the ethylene glycol solution of maleic acid dropwise. The ethylene glycol dispersion of the hydrotalcite precursor is heated to reflux temperature for 6 hours, washed and dried to obtain a maleic acid intercalated hydrotalcite. The chemical formula is as follows: Mg ₀ . ₆₇ Al ₀ . ₃₃ (OH) ₂ (C ₄ H ₂ O ₄ ) ₀ . ₁₇ '0.6H ₂ O.

The XRD spectrum is shown in Fig. 1. As can be seen from the figure, the characteristic diffraction peak of (003) is advanced to 7.1. Left and right, it is proved that the maleate enters into the layer of MgAl-LDHs, and the MgAl-maleate-LDHs intercalation product is obtained, and the intercalated LDHs maintain the layered structure of the precursor well. Example 2:

Step A. 8.20 g of Mg(N0 ₃ ) ₂ · 6H ₂ 0, 3.17 g of Zn(N0 ₃ ) ₂ · 6H ₂ 0 and 8.00 g of A1(N0 ₃ ) ₃ · 9H ₂ 0 are dissolved in deionized C0 ₂ 80 ml of a mixed salt solution was prepared in water, and 4.70 g of NaOH was dissolved in deionized water de-C0 ₂ to prepare 80 ml of an alkali solution. The two solutions were simultaneously added to the reactor for 1 min, crystallized at 1000 ° C for 6 hours under N ₂ protection, filtered, and washed with deionized water de C0 ₂ to obtain 5.63 g of Mg: Zn: Al = 3: 1: 2 precursor filter cake MgZnAl-NO _r LDHs.

Step B. Disperse the above MgZnAl-N0 ₃ -LDHs precursor filter cake in 10 ml of ethylene glycol, and dissolve 4.96 g of maleic acid in 10 ml of ethylene glycol to control pH>4.0, maleic acid The ethylene glycol solution is added dropwise to the ethylene glycol dispersion of the hydrotalcite precursor, heated to reflux, and reacted for 1 hour. After washing and drying, the maleic acid intercalated hydrotalcite is obtained and determined by elemental analysis. The chemical formula is: M _{g0 50} Zn ₀ . ₁₇ Al ₀ . ₃₃ (OH) ₂ (C ₄ H ₂ O ₄ ) ₀ . ₁₇ . 0.53⁄4O.

The IR spectrum is shown in Fig. 2. It can be seen from the figure that the intercalated product exhibits a C=C stretching vibration peak at 1636 cm ^-1 , indicating that the double bond in the organic anion is maintained.

 The TG-DTA curve is shown in Fig. 3. As can be seen from the figure, the decomposition temperature of maleic acid is raised to 264 °C. Example 3:

Step A. Dissolve 7.68 g of Mg(N0 ₃ ) ₂ ■ 6H ₂ 0, 8.92 g of Zn(N0 ₃ ) ₂ ' 6H ₂ 0 and 11.25 g of A1(N0 ₃ ) ₃ · 9H ₂ 0 in deionized C0 ₂ 40 ml of a mixed salt solution was prepared in water, and 7.28 g of NaOH was dissolved in deionized water de C0 ₂ to prepare 40 ml of an alkali solution. The two solutions were simultaneously added to the reactor for 4 min, and recrystallized at 100 ° C for 6 hours under N ₂ protection. The obtained product was washed with deionized water de-C0 ₂ and filtered to give 8.54 g of MgZnAl-N0 ₃ -LDHs precursor filter cake of Mg: Zn: Al = 1: 1:1.

Step B. Disperse the above MgZnA O _r LDHs precursor filter cake in 13 ml of ethylene glycol, dissolve 5.22 g of maleic acid in 9 ml of ethylene glycol, control pH>4.0, and drop the ethylene glycol solution of maleic acid. The ethylene glycol dispersion of the hydrotalcite precursor was added, heated to reflux, and reacted for 4 hours, and washed and dried to obtain a maleic acid intercalated hydrotalcite. The chemical formula is determined by elemental analysis: Mg ₀ . ₃₃ Zn ₀ . ₃₃ Al ₀ . ₃₃ (OH) ₂ (C ₄ H ₂ O ₄ ) ₀ . ₁₇ · 0·63⁄4Ο. Example 4:

Step 将. 8.20 g Mg(N0 ₃ ) ₂ · 6H ₂ 0, 3.17 g Zn(N0 ₃ ) ₂ ■ 6H ₂ 0 and 4.00 g A1(N0 ₃ ) ₃ · 9H ₂ 0 are dissolved in C ( _3⁄4 ) dubbed 40ml DI water mixed salt solution, 4.59 g NaOH dissolved in deionized water and C0 ₂ removal formulated 40ml of alkali solution. the two solutions were simultaneously added to the reactor for 5min, at reflux under N ₂ at 85 ° C After crystallization for 7 hours, it was filtered and washed with deionized water de-C0 ₂ to obtain 4.28 g of Mg:Al:3:1:1 precursor filter cake MgZnAl-N0 ₃ -LDHs.

Step B. Disperse the above MgZnAl-N0 ₃ -LDHs precursor filter cake in 38 ml of ethylene glycol, and dissolve 3.09 g of maleic acid in 3.10 ml of ethylene glycol to control pH>4.0, and the maleic acid of ethylene The alcohol solution was added dropwise to the ethylene glycol dispersion of the hydrotalcite precursor, heated to reflux, and reacted for 2 hours, and washed and dried to obtain a maleic acid intercalated hydrotalcite. The chemical formula was determined by elemental analysis: Mgo.6oZno.2oAlo.2o(OH) ₂ (C ₄ H ₂ 04)on · 0.4H ₂ O. Example 5:

Step A. 8.20 g of Mg(N0 ₃ ) ₂ · 6H ₂ 0, 2.53 g of Ca(N0 ₃ ) ₂ ' 4H ₂ 0 and 5.14 g of Ni(N0 ₃ ) _{3 were} dissolved in deionized water de C0 ₂ to prepare 210. The salt solution was mixed with ml, and 6.10 g of NaOH was dissolved in deionized water de C0 ₂ to prepare 210 ml of an alkali solution. The two solutions were simultaneously added to the reactor for 6 min, and the resulting slurry was recrystallized at 100 ° C for 6 hours under N ₂ protection. Filtration and washing with deionized water de-C0 ₂ gave 4.52 g of a MgCaNi-N0 ₃ -LDHs precursor filter cake of Mg: Ca: Ni = 3 : 1 : 2 .

Step B. Disperse the above MgCaNi-NO LDHs precursor filter cake in 30 ml of ethylene glycol, dissolve 4.05 g of maleic acid in 5.05 ml of ethylene glycol, control pH>4.0, and add ethylene glycol solution of maleic acid. The mixture was added dropwise to the ethylene glycol dispersion of the hydrotalcite precursor, heated to reflux, and reacted for 3 hours. After washing, the maleic acid intercalated hydrotalcite was obtained. The chemical formula was determined by elemental analysis: Mgo.5oCao.i7 io.33(OH) ₂ (C ₄ H ₂ 04)o. ₁ 7 · 0.7H ₂ O. Example 6

Step A. 8.20 g of Mg(N0 ₃ ) ₂ · 6H ₂ 0, 3.17 g of Zn(N0 ₃ ) ₂ · 6H ₂ 0 and 8.00 g of A1(N0 ₃ ) ₃ · 9H ₂ 0 are dissolved in deionized C0 ₂ 60 ml of a mixed salt solution was prepared in water, and 5.60 g of NaOH was dissolved in deionized water de C0 ₂ to prepare 60 ml of an alkali solution. The two solutions were simultaneously added to the reactor at the same flow rate for 0.5 min by means of a metering pump, and the resulting slurry was crystallized at 90 ° C for 6 hours under the protection of 3⁄4. The resulting product was washed with deionized water, removal of C0 ₂ and filtered to give 5.63 g Mg: Zn: Al = 3: MgZnAl-N0 3 -LDHs precursor cake 2: 1.

Step B. Disperse the above MgZnAl-N0 ₃ -LDHs precursor filter cake in 10 ml of ethylene glycol, dissolve 2.5 g of acrylic acid in 5 ml of ethylene glycol, control pH>4.0, and drop the ethylene glycol solution of acrylic acid. Adding to the ethylene glycol dispersion of the hydrotalcite precursor, heating to reflux, reacting for 6 hours, washing and drying to obtain an acrylic intercalated hydrotalcite, which is determined by elemental analysis and has the chemical formula: Mg ₀ . ₅₀ Zn ₀ . ₁₇ Al ₀ . ₃₃ (OH) ₂ (C ₃ H ₂ O ₄ ) ₀ . ₁₇ ' 0.53⁄4O. Example 7

Step A. Dissolve 10.26 g of Mg(N0 ₃ ) ₂ · 6H ₂ 0 and 7.50 g of A1(N0 ₃ ) ₃ · 9H ₂ 0 in deionized water de C0 ₂ to prepare 50 ml mixed salt solution, dissolve 4.8 g NaOH A 50 ml alkali solution was prepared in deionized water de C0 ₂ . The two solutions were simultaneously added to the reactor for 3 min, recrystallized at 100 ° C for 6 hours under N ₂ protection, filtered, and washed with deionized water of CO ₂ to obtain 4.87 g of Mg: Al = 2: 1 Hydrotalcite precursor filter cake MgAl-N0 ₃ -LDHs.

Step B. Disperse the above hydrotalcite precursor filter cake in 20 ml of ethylene glycol, dissolve 1.44 g of acrylic acid in 7.0 ml of ethylene glycol, control pH > 4.0, and add the ethylene glycol solution of acrylic acid to the hydrotalcite precursor. The ethylene glycol dispersion was heated to reflux temperature for 6 hours, washed and dried to obtain an acrylic intercalated hydrotalcite. The chemical formula is as follows: Mg ₀ . ₆₇ Al ₀ . ₃₃ (OH) ₂ (C ₃ H ₂ O ₄ ) ₀ . ₁₇ · 0·6Η ₂ Ο. Comparative example:

The double bond anion intercalated hydrotalcite obtained in Examples 1-7 and the common magnesium aluminum hydrotalcite were respectively obtained. (The chemical formula is Mgo. ₆₇ Alo. ₃₃ (OH)(C0 ₃ )o. ₁₇ · 0.4H ₂ O ) is added to 100 parts of PVC according to the amount listed in Table 1, and 50 parts of phthalic acid is added. Diisooctyl acid ester (DOP) and 2 parts of calcium stearate, 0.5 parts of zinc stearate, kneaded at 140 ° C for 10 minutes on a SSR-Z4 plastic laboratory machine, and pressed to a thickness of 150 ° C. A 1 mm sheet was cut into pieces of 1 cm x 1 cm. The test piece was placed in a heat aging test chamber at 180 ± 1 ° C for static aging test, and the time at which the black decomposition of the test piece began to appear was set as the heat stabilization time, and the results are shown in Table 1.

 Table 1

 From the comparative data in Table 1, it is seen that the double bond anion intercalated hydrotalcite has a significantly improved thermal stability compared to the hydrothermal talc containing no double bond anion intercalation.

Claims

Claim

1. An organic anion intercalated hydrotalcite containing a Huan key, the chemical composition of which is:

Wherein M ²⁺ represents one or two of a divalent metal cation Mg ²⁺ , Zn ²⁺ , Ca ²⁺ , C _U ²⁺ , Ni ²⁺ , Co ²⁺ , Mn ²⁺ , Cd ²⁺ ;

M ³⁺ represents one of a trivalent metal cation Al ³⁺ , Ni ³⁺ , Co ³⁺ , Fe ³⁺ , Mn ³⁺ , Cr ³⁺ , V ³⁺ , Ti ³⁺ ;

A ⁿ - is one of a double bond organic anion maleate, propionate, butenoate, aminobutenoic acid, oleic acid, linoleate, linolenate;

X is the mole fraction of M ³⁺ ions, and its value ranges from 0.2 x <0.33;

 m is the amount of crystal water, and its value ranges from 0 < m < 2.

According to claim 1 containing the keys Han hydrotalcite intercalated organic anions, wherein said M ²⁺ is Mg ^2+, Zn ^2+, Ca ²⁺ is one or two; M ^{3 +} is Al ³⁺ or Ni ³⁺ ; A ⁿ - is maleate, propionate or butenoate.

3. The double bond-containing organic anion of the hydrotalcite intercalated in claim 1, wherein said A ⁿ - is a maleate.

 4. The double bond organic anion intercalated hydrotalcite according to claim 1 is used as a heat stabilizer in PVC.