Crosslinking agent, polymer composition containing crosslinking agent, and crosslinked product of same

Abstract

A crosslinking agent which is based on an aluminate complex salt of a hydroxyl group-containing organic compound, which crosslinks a carboxy group and a nitrile group. When the crosslinking agent is added to a carboxy group-denatured NBR latex, gloves having flexibility and a strength comparable to those of natural rubber gloves can be manufactured. Furthermore, the excellent creep resistance is a big characteristic. Moreover, unlike normal sulfur vulcanization gloves, the gloves do not contain sulfur and a vulcanization accelerator, and do not necessarily require addition of zinc oxide.

Claims

1. A crosslinking agent comprising: a neutralized product of an aluminate complex salt of a hydroxyl group-containing organic compound; a divalent metal ion Ca.sup.2+, Mg.sup.2+, or Zn.sup.++ bound product of the aluminate complex salt of a hydroxyl group-containing organic compound; or a reaction product with a carboxylic acid of the aluminate complex salt of a hydroxyl group-containing organic compound.

2. The crosslinking agent according to claim 1, wherein the hydroxyl group-containing organic compound is a monohydric or polyhydric alcohol; a polyether polyol; a polyester polyol; a hydroxyl group-containing polymer selected from polyvinyl alcohol, carboxymethylcellulose, hydroxyethylcellulose, starch, dextrin, cyclodextrin, oligosaccharide, guar gum, alginic acid, pectin, and xanthane gum; a carbohydrate; or a hydroxycarboxylic acid.

3. A polymer composition, comprising a polymer and a crosslinking agent comprising: a neutralized product of an aluminate complex salt of a hydroxyl group-containing organic compound; a divalent metal ion Ca.sup.2+, Mg.sup.2+, or Zn.sup.++ bound product of the aluminate complex salt of a hydroxyl group-containing organic compound; or a reaction product with a carboxylic acid of the aluminate complex salt of a hydroxyl group-containing organic compound.

4. The polymer composition according to claim 3, wherein the neutralized product of an aluminate complex salt of a hydroxyl group-containing organic compound is neutralized by directly blending the aluminate complex salt into the polymer composition.

5. The polymer composition according to claim 3, wherein the polymer contains a carboxy group and/or a nitrile group.

6. The polymer composition according to claim 3, wherein the polymer is a carboxy-denatured NBR latex or SBR latex, a carboxy group-containing chloroprene latex, a carboxy group-containing polyurethane dispersion, a carboxy group-containing acrylic emulsion, a carboxy group-containing water-based polyester, or a carboxylic acid-denatured water-based resin.

7. The polymer composition according to claim 3, further comprising one or two or more organic compounds selected from an internal sizing agent, a surface sizing agent, polyvinyl alcohol, polyethylene oxide, carboxymethylcellulose, starch, dextrin, cyclodextrin, oligosaccharide, guar gum, alginic acid, pectin, and xanthane gum.

8. The polymer composition according to claim 3, further comprising magnesium oxide, magnesium hydroxide, or colloidal magnesium hydroxide.

9. A crosslinked molded product obtained by molding and crosslinking the polymer composition according to claim 3.

10. The crosslinked molded product according to claim 9, wherein the molded product is surface-treated with highly basic aluminum chloride, highly basic aluminum nitrate, an internal sizing agent, a surface sizing agent, or a crosslinking agent comprising: a neutralized product of an aluminate complex salt of a hydroxyl group-containing organic compound; a divalent metal ion Ca.sup.2+, Mg.sup.2+, or Zn.sup.++ bound product of the aluminate complex salt of a hydroxyl group-containing organic compound; or a reaction product with a carboxylic acid of the aluminate complex salt of a hydroxyl group-containing organic compound.

11. The crosslinked molded product according to claim 9, wherein the molded product is a dip molded article or a paper product.

12. The crosslinking agent according to claim 1, the crosslinking agent is a crosslinking agent of a carboxy group and/or a nitrile group.

13. The crosslinking agent according to claim 1, wherein the neutralized product of an aluminate complex salt of a hydroxyl group-containing organic compound is a carbon dioxide reaction product of an aluminate complex salt of a hydroxyl group-containing organic compound.

14. The polymer composition according to claim 3, wherein the neutralized product of an aluminate complex salt of a hydroxyl group-containing organic compound is a carbon dioxide reaction product of an aluminate complex salt of a hydroxyl group-containing organic compound.

15. The crosslinked molded product according to claim 9, wherein the neutralized product of an aluminate complex salt of a hydroxyl group-containing organic compound is a carbon dioxide reaction product of an aluminate complex salt of a hydroxyl group-containing organic compound.

16. The crosslinking agent according to claim 1, wherein the hydroxyl group-containing organic compound is a polymer polyol.

Description

DESCRIPTION OF EMBODIMENTS

(1) Many reaction systems in which the present crosslinking agent is used are water-based. Moreover, many aluminate complex salts of a hydroxyl group-containing organic compound are water-soluble. Therefore, desirably, neutralized products of aluminate complex salts of a hydroxyl group-containing organic compound are also water-soluble. However, neutralized products of monohydric alcohol or dihydric alcohol aluminate complex salts become water-insoluble in many cases due to lack of water-soluble functional groups, but reactants neutralized by some organic acids maintain water solubility. In this regard, however, in carbon dioxide-neutralized products of polyhydric alcohol or hydroxycarboxylic acid-based aluminate complex salts, the neutralized products may maintain water solubility even when hydroxyl groups are completely formed into aluminate complex salts.

(2) Moreover, various qualities are required for a crosslinked molded product. Therefore, the diversity of qualities of the crosslinking agent is also important as well as the diversity of raw materials to be crosslinked (organic compounds containing a hydroxyl group). Thus, desirably, a polyhydric alcohol, a carbohydrate, or a hydroxycarboxylic acid, having multiple hydroxyl groups is selected as a crosslinking agent raw material, and the coordination number of an aluminate is selected depending on the intended use.

(3) More specifically, 1-5 or 6 equivalents of the aluminate are added to, for example, sorbitol, fructose, or a gluconate, to synthesize an aluminate complex salt, the aluminate complex salt is directly blended into, or partially or completely neutralized by an acid, and then blended into a raw material to be crosslinked, the quality of a crosslinked molded product is measured, and a crosslinking agent adapted for the purpose is selected.

(4) In the case of a normal carboxylated latex, regarding the additive amount of the crosslinking agent, 0.2-0.3 parts in terms of Al.sub.2O.sub.3 are appropriate in many cases, but the crosslinking agent can be used within the range of 0.1-3.0 parts depending on the use.

(5) In the case of manufacturing dip molded articles, the pH of a latex prepared liquid is around 9.5-10.0. An alkali may be added to the above blended latex, or the aluminate complex salt may be directly added to the latex stock solution to be a neutralized product, and then the pH may be adjusted by adding an alkali.

EXAMPLES

(6) (Synthesis of Crosslinking Agent)

(7) 1. Synthesis Reaction and Properties of Crosslinking Agent

(8) The Na/Al ratio of sodium aluminate to be used is not particularly limited, and the sodium aluminate used herein is sodium aluminate NA-170 manufactured by ASAHI Chemical Co., Ltd.

(9) Analysis Values Al.sub.2O.sub.3 18.73% Na.sub.2O 19.37% Molar Ratio 1.70

(10) The above sodium aluminate is diluted and adjusted to be 2.0 mol/L (in terms of NaAlO.sub.2) as NaAlO.sub.2.

(11) In contrast, a hydroxyl group-containing organic compound is adjusted to be a 2.0 mol/L solution (in terms of hydroxyl groups) and diluted depending on the number of aluminate complex salts to be introduced. Specifically, when introducing n of aluminate complex salts (n-valent aluminate complex salt), the hydroxyl group-containing organic compound is diluted by n times.

(12) An equivalent 2.0 molar sodium aluminate solution is added while being stirred to the above diluted hydroxyl group-containing organic compound solution at normal temperature, and the mixture is left for two hours, so that a hydroxyl group-containing organic compound aluminate complex salt is synthesized.

(13) First, syntheses of a sorbitol-4Al aluminate complex salt, a gluconic acid-4Al aluminate complex salt, and neutralized products thereof and properties thereof will be described.

(14) When adding a calcium nitrate tetrahydrate 10% solution to a 2.0 molar sodium aluminate solution in terms of NaAlO.sub.2, calcium aluminate is precipitated. Whether sodium aluminate remains can be determined.

(15) (1) Syntheses of Sorbitol (Hexahydric Alcohol)-4Al Aluminate Complex Salt and Gluconic Acid (Pentahydric Alcohol)-4Al Aluminate Complex Salt

(16) To each of 100 ml of a 0.5 molar sorbitol aqueous solution and 100 ml of a 0.5 molar sodium gluconate aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that a sorbitol-4Al aluminate complex salt and a gluconic acid-4Al aluminate complex salt were synthesized. They both were water-soluble.

(17) (2) Addition Test (1) of Calcium Nitrate Solution

(18) To each of the above reaction solutions, 10 ml of a 10% calcium nitrate tetrahydrate solution was added. Calcium aluminate was not precipitated. This indicates that sodium aluminate did not remain.

(19) However, after a lapse of one hour, the whole reaction solution of the sorbitol-4Al aluminate complex salt to which calcium nitrate was added gelated.

(20) In contrast, the gluconic acid-4Al aluminate complex salt maintained water solubility.

(21) It is considered that the sorbitol-4Al aluminate complex salt (anionic) gelated because the complex salt is bonded due to substitution of Na.sup.+ with Ca.sup.2+, but the gluconic acid-4Al aluminate complex salt maintained water solubility because of containing a carboxy group.

(22) (3) Neutralization of Sorbitol (Hexahydric Alcohol)-4Al Aluminate Complex Salt and Gluconic Acid (Pentahydric Alcohol)-4Al Aluminate Complex Salt

(23) Carbon dioxide was added to each of the above aluminate complex salt solutions to adjust the pH to 8.3-8.5, so that carbon dioxide-neutralized products of the sorbitol (hexahydric alcohol)-4Al aluminate complex salt and the gluconic acid (pentahydric alcohol)-4Al aluminate complex salt were synthesized.

(24) (4) Addition Test (2) of Calcium Nitrate Solution

(25) In the same manner as (3), the addition test of the calcium nitrate solution was performed. However, in the neutralized solution of the sorbitol-4Al aluminate complex salt, precipitation and gelation of calcium aluminate did not occur. The sorbitol (hexahydric alcohol)-4Al aluminate complex salt became a neutralized product, thereby being non-ionic, bonding by Ca.sup.2+ was not generated, and gelation did not occur.

(26) In contrast, in the neutralized product of the gluconic acid-4Al aluminate complex salt, a precipitate was temporarily generated during the addition of the calcium nitrate solution but disappeared rapidly. It is considered that the precipitation temporarily occurred because Ca.sup.2+ reacted with a carboxy group of the neutralized product of the gluconic acid-4Al aluminate complex salt.

(27) 2. Syntheses of Various Hydroxyl Group-Containing Organic Compound Aluminate Complex Salts

(28) 1) Synthesis of Ethanol (Monohydric Alcohol)-1Al Aluminate Complex Salt

(29) To 100 ml of a 2 molar ethanol aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that an ethanol-1Al aluminate complex salt was synthesized.

(30) Even when a calcium nitrate solution was added to the synthesized solution, a precipitate of calcium aluminate was not generated. This indicates that sodium aluminate did not remain.

(31) The reaction solution gradually (after about six hours) became cloudy when being stored in the air for a long time, and the wall of a container was covered with a precipitate after a few days. It is considered that the ethanol-1Al aluminate complex salt was insolubilized by absorbing carbon dioxide in the air.

(32) 2) Syntheses of Ethylene Glycol (Dihydric Alcohol)-1Al Aluminate Complex Salt and Ethylene Glycol-2Al Aluminate Complex Salt

(33) To each of 100 ml of a 2 molar ethylene glycol erythritol aqueous solution and 100 ml of a 1 molar ethylene glycol aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that an ethylene glycol-1Al aluminate complex salt and an ethylene glycol-2Al aluminate complex salt were synthesized. Even when a calcium nitrate solution was added to each of the synthesized solutions, a precipitate of calcium aluminate was not generated.

(34) Moreover, when each of the reaction solutions was stored in the air for a few days, crystals were generated.

(35) 3) Syntheses of Erythritol (Tetrahydric Alcohol)-2Al Aluminate Complex Salt and Erythritol-4Al Aluminate Complex Salt

(36) To each of 100 ml of a 1 molar ethylene glycol aqueous solution and 100 ml of a 0.5 molar ethylene glycol aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that an erythritol-2Al aluminate complex salt and an erythritol-4Al aluminate complex salt were synthesized. Even when a calcium nitrate solution was added to each of the synthesized solutions, a precipitate of calcium aluminate was not generated.

(37) 4) Syntheses of Sorbitol (Hexahydric Alcohol)-2Al, 4Al, and 6Al Aluminate Complex Salts

(38) To each of 100 ml of a 1 molar sorbitol aqueous solution, 100 ml of a 0.5 molar sorbitol aqueous solution, and 100 ml of a 1/3 molar sorbitol aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that a sorbitol-2Al aluminate complex salt, a sorbitol-4Al aluminate complex salt, and a sorbitol-6Al aluminate complex salt were synthesized. Even when a calcium nitrate solution was added to each of the synthesized solutions, a precipitate of calcium aluminate was not generated.

(39) 5) Syntheses of Carbohydrate Fructose (Pentahydric Alcohol)-2Al Aluminate Complex Salt and Fructose-3Al Aluminate Complex Salt

(40) To each of 100 ml of a 1 molar fructose aqueous solution and 100 ml of a 2/3 molar fructose aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that a fructose-2Al aluminate complex salt and a fructose-3Al aluminate complex salt were synthesized. Even when a calcium nitrate solution was added to each of the synthesized solutions, a precipitate of calcium aluminate was not generated.

(41) However, degeneration occurred by a Maillard reaction after a lapse of time from the synthesis, and the reaction solution was colored, but the functions as a crosslinking agent were maintained.

(42) 6) Syntheses of Hydroxycarboxylic Acid Aluminate Complex Salts

(43) (1) Syntheses of Gluconic Acid (Pentahydric Alcohol Carboxylic Acid)-2Al, -4Al, and -5Al Aluminate Complex Salts

(44) To each of 100 ml of a 1 molar sodium gluconate aqueous solution, 100 ml of a 0.5 molar sodium gluconate aqueous solution, and 100 ml of a 0.4 molar sodium gluconate aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that a gluconic acid-2Al aluminate complex salt, a gluconic acid-4Al aluminate complex salt, and a gluconic acid-5Al aluminate complex salt were synthesized. Even when a calcium nitrate solution was added to each of the synthesized solutions, a precipitate of calcium aluminate was not generated.

(45) (2) Synthesis of Tartaric Acid (Dihydric Alcohol Dicarboxylic Acid)-2Al Aluminate Complex Salt

(46) To 100 ml of a 1 molar sodium gluconate tartaric acid aqueous solution, 100 ml of a 2 molar sodium aluminate (in terms of NaAlO.sub.2) was added while being stirred, and the mixture was reacted for two hours, so that a tartaric acid-2Al aluminate complex salt was synthesized. Even when a calcium nitrate solution was added to the synthesized solution, a precipitate of calcium aluminate was not generated.

(47) 6) Syntheses 7) Syntheses of Polymer Polyol Aluminate Complex Salts

(48) (1) Synthesis of Carboxymethylcellulose Aluminate Complex Salt

(49) To 150 g of a CMC Daicel 1110 (Daicel FineChem Ltd., the degree of etherification 0.72, 2% viscosity 113 mPa.$) 2% aqueous solution, 3.4 g of the above sodium aluminate (Al.sub.2O.sub.3 18.73%) was added, and the mixture was reacted for two hours, so that an aluminate complex salt including nearly one aluminate complex salt per one cellulose residue was synthesized. The reaction solution was water-soluble but became slightly turbid. Even when a calcium nitrate solution was added to the synthesized solution, a precipitate of calcium aluminate was not generated. However, the reaction solution to which calcium nitrate was added gelated in a short time.

(50) (2) Synthesis of Polyvinyl Alcohol Aluminate Complex Salt

(51) For synthesis of the above aluminate complex salt, powder sodium aluminate with less Na content was used in consideration of a deacetylation reaction of polyvinyl alcohol under a strong alkaline condition. The powder sodium aluminate is sodium aluminate NA-120 manufactured by ASAHI Chemical Co., Ltd.

(52) Analysis Values Al.sub.2O.sub.3 53.6% Na.sub.2O 39.7% Molar Ratio 1.22

(53) (2-1) Synthesis of Carboxy-Denatured Polyvinyl Alcohol Aluminate Complex Salt

(54) To a carboxy-denatured PVA (J POVAL AF-17; manufactured by JAPAN VAM & POVAL CO., LTD.) 10% solution, 3.8 g of powder sodium aluminate (10% solution) in terms of Al.sub.2O.sub.3 was added, so that a carboxy-denatured polyvinyl alcohol aluminate complex salt was synthesized. The reaction solution was water-soluble. Even when a calcium nitrate solution was added to the synthesized solution, a precipitate of calcium aluminate was not generated. However, the reaction solution to which calcium nitrate was added gelated in a short time.

(55) (2-2) Synthesis of Easily Water-Soluble Polyvinyl Alcohol Aluminate Complex Salt

(56) To 100 g of an easily water-soluble PVA (EF-05; manufactured by JAPAN VAM & POVAL CO., LTD.) 10% solution, which was dissolved at normal temperature, 3.8 g of powder sodium aluminate (10% solution) in terms of Al.sub.2O.sub.3 was added, so that a polyvinyl alcohol aluminate complex salt was synthesized. The reaction solution was water-soluble. Even when a calcium nitrate solution was added to the synthesized solution, a precipitate of calcium aluminate was not generated. However, the reaction solution to which calcium nitrate was added gelated in a short time.

(57) 3. Syntheses of Neutralized Substances of Hydroxyl Group-Containing Organic Compound Aluminate Complex Salts

(58) 1) Neutralization of Hydroxyl Group-Containing Organic Compound Aluminate Complex Salts by Carbon Dioxide

(59) By adding an acid (inorganic acid) or an acid salt to the above n-valent aluminate complex salt (hydroxyl group-containing organic compound (—O—Al(OH).sub.3.sup.−Na.sup.+).sub.n) and adjusting the pH to 7-9, so that a neutralized product of an aluminate complex salt (assumed as hydroxyl group-containing organic compound (—O—Al(OH).sub.2).sub.n) can be synthesized. Here, the neutralization was performed by adding carbon dioxide. The pH was set to be around 8.5 as in a sodium hydrogen carbonate solution.

(60) In place of carbon dioxide, an inorganic acid such as hydrochloric acid, nitric acid, sulfuric acid, or boric acid may be used. Moreover, an organic acid other than a carboxylic acid may be used. Moreover, an acid salt such as potassium dihydrogen phosphate may be used.

(61) (1) Neutralization of Monohydric Alcohol Aluminate Complex Salt (Ethyl Alcohol-1Al Aluminate Complex Salt) or Dihydric Alcohol Aluminate Complex Salt (Ethylene Glycol-2Al Aluminate Complex Salt)

(62) An ethyl alcohol-1Al aluminate complex salt or a dihydric alcohol aluminate complex salt (ethylene glycol-aluminate complex salt) was stored in the air for a long period, a precipitate was generated. Moreover, when the neutralization was performed by carbon dioxide, a precipitate was generated in the same manner.

(63) (2) Neutralization of More Than Trihydric Alcohol (Erythritol) Aluminate Complex Salt

(64) In neutralization of a more than trihydric alcohol (erythritol or the like) aluminate complex salt by carbon dioxide, a product maintained water solubility.

(65) Moreover, even when calcium nitrate tetrahydrate was added to the neutralized solution, a precipitate was not generated.

(66) (3) Neutralization of Hydroxycarboxylic Acid Aluminate Complex Salts

(67) All neutralized products of hydroxycarboxylic acid aluminate complex salts were water-soluble.

(68) Moreover, even when calcium nitrate was added to the neutralized solution, a precipitate was not generated.

(69) (4) Neutralization of Carboxymethylcellulose Aluminate Complex Salt A neutralized product of a carboxymethylcellulose aluminate complex salt by carbon dioxide was water-soluble, but slightly took on a milky white color.

(70) Moreover, even when calcium nitrate was added to the neutralized solution, a precipitate was not generated.

(71) 2) Neutralization of Hydroxyl Group-Containing Organic Compound Aluminate Complex Salt by Organic Carboxylic Acid

(72) Although a hydroxyl group-containing organic compound aluminate complex salt can be neutralized by an organic carboxylic acid, a neutralized product of the hydroxyl group-containing organic compound aluminate complex salt reacts with a carboxylic acid. Therefore, a part of the crosslinking agent is consumed by the reaction with the carboxylic acid, and thus the neutralization by the organic carboxylic acid is basically undesirable. However, the neutralization by the organic carboxylic acid can be used to contribute to the adjustment of crosslinking strength due to a decrease in the crosslinking point number of the crosslinking agent, the improvement in hydrophilicity, provision of water solubility, and the like. Neutralization of an ethylene glycol-2Al aluminate complex salt by a carboxylic acid will be described below as an example.

(73) (1) Reaction of Ethylene Glycol-2Al Aluminate Complex Salt with Carboxylic Acid

(74) Properties of neutralized products are different from one another depending on the types and properties of carboxylic acids.

(75) Thus, for the ethylene glycol-2Al aluminate complex salt whose reaction with a carboxylic acid is easy to be observed, a reaction with a carboxylic acid was examined.

(76) (i) Reaction with Maleic Acid (Dicarboxylic Acid)

(77) Even when the amount of maleic acid, at which excess Na.sup.+ is neutralized, was added such that the equivalent of ethylene glycol (—O—Al(OH).sub.3.sup.−Na.sup.+).sub.2 was obtained, the water solubility was maintained. It is considered that, the excess Na.sup.+ (equivalent to 0.7) of sodium aluminate having Na/Al=1.7 is simply neutralized by maleic acid in this range, and the ethylene glycol-2Al aluminate complex salt was not reacted with maleic acid.

(78) However, by adding maleic acid that neutralizes Na.sup.+ that is the half of the amount of Na.sup.+ equivalent to ethylene glycol (—O—Al(OH).sub.3.sup.−N.sup.+).sub.2, a precipitate was generated.

(79) (ii) Reaction with Malic Acid (Hydroxy Dicarboxylic Acid)

(80) In the same manner as the above, even when malic acid was added such that the equivalent of ethylene glycol (—O—Al(OH).sub.3.sup.−Na.sup.+).sub.2 was obtained, the water solubility was maintained.

(81) However, by adding malic acid that neutralizes Na.sup.+ that is ⅔ of the amount of Na.sup.+ equivalent to ethylene glycol (—O—Al(OH).sub.3.sup.−Na.sup.+).sub.2, the whole liquid gelated. Clearly, malic acid was crosslinked. Moreover, this fact indicates that, even if all Na.sup.+ are not neutralized by an acid, a carboxy group is crosslinked by neutralization of about ⅔ of the neutralization equivalent.

(82) (iii) Reaction with Citric Acid (Hydroxy Tricarboxylic Acid)

(83) Even when citric acid that neutralizes all Na.sup.+ of the ethylene glycol-2Al aluminate complex salt was added, a citric acid-neutralized product of the ethylene glycol-2Al aluminate complex salt maintained water solubility.

(84) Assuming from the reaction with malic acid, it is considered that citric acid was also crosslinked, and the water solubility was maintained because of one more carboxy group having high hydrophilicity.

(85) Therefore, by the neutralization with citric acid, the neutralized product of the ethylene glycol-2Al aluminate complex salt can be maintained to be water-soluble.

(86) The citric acid-neutralized product was gradually thickened after a lapse of two weeks. This indicates that citric acid was also crosslinked.

(87) 4. Manufacture of Crosslinking Agent-Containing NBR Latex Compositions (Compound Latexes)

(88) Each of 0.2 parts (as Al.sub.2O.sub.3) of the above CO.sub.2-neutralized product of the erythritol-2Al aluminate complex salt (1) and 0.2 parts (as Al.sub.2O.sub.3) of the above CO.sub.2-neutralized product of the erythritol-4Al aluminate complex salt (2) was added while being stirred to an NBR latex stock solution.

(89) Powder sodium aluminate was used as sodium aluminate. The composition of the powder sodium aluminate is as follows.

(90) NaAlO.sub.2 Al.sub.2O.sub.3 content 54.1% Na/Al=1.25

(91) (Results)

(92) (1) Blending Stability Test

(93) The above crosslinking agent-blended latex was filtered by a 200-mesh metal sieve, and a crosslinking agent-blended stability test was performed. An aggregate was not observed (refer to Table 1).

(94) The used NBR latex is KLN 830 manufactured by Kumho.

(95) Latex Concentration 44.8% pH 8.4

(96) (2) Pot Life Test of Blended Latex

(97) The above crosslinking agent-blended latex was stored at normal temperature, and a pot life was tested. Generation of an aggregate was not observed even after storing for 60 days or more (refer to Table 1).

(98) (Evaluation)

(99) According to the above results, a high-concentration latex in which additives such as sulfur, zinc oxide, a vulcanization accelerator, an antioxidant, and a chlorine ion are not contained at all and only a water-soluble crosslinking agent is blended can be stably blended. Therefore, market supply as an NBR latex compound became possible.

(100) 5. Hydroxyl Group-Containing Organic Compound Aluminate Complex Salts and/or Neutralized Substance Crosslinking Agent-Blended NBR Latexes Thereof

(101) The used NBR latex is the above KLN 830 manufactured by Kumho.

Comparative Example 1

(102) Composition Liquid for Sulfur Vulcanization Dipped Products

(103) Additive Agent KOH 1.6 parts ZnO 1.25 parts S 1.0 part BZ 0.2 parts

(104) (Dibutyldithiocarbamic Acid Zinc)

(105) By adding the above chemical to water, the latex concentration was adjusted to 30%.

Reference Example

(106) The physical properties were measured using commercial natural rubber gloves.

Example 1

(107) By adding water to a compound latex liquid to which 0.25 parts in terms of Al.sub.2O.sub.3 of the carbon dioxide-neutralized product of the erythritol-2Al aluminate complex salt was added, the latex concentration was adjusted to 30%, and by adding a 10% KOH solution, the pH was adjusted to 9.6.

Example 2

(108) After 0.25 parts (in terms of Al.sub.2O.sub.3) of the erythritol-4Al aluminate complex salt synthesized using powder sodium aluminate was directly added to a latex liquid, the latex concentration was adjusted to 30%.

(109) Then, by adding a 10% KOH solution, the pH was adjusted to 9.7.

Example 3

(110) Colloidal magnesium hydroxide was prepared as follows.

(111) To a liquid composed of 16.2 g of a 10% potassium hydroxide solution and 24.7 g of water, 34.1 g of a MgCl.sub.2.6H.sub.2O 5% aqueous solution (0.5 phr in terms of MgO) was added while being stirred. Next, the generated colloidal magnesium hydroxide solution was added to a compound latex liquid to which 0.25 parts in terms of Al.sub.2O.sub.3 of the carbon dioxide-neutralized product of the erythritol-2Al aluminate complex salt was added, so that a 30% latex liquid was obtained.

Example 4

(112) To a compound latex liquid to which 0.25 phr in terms of Al.sub.2O.sub.3 of the carbon dioxide-neutralized product of the erythritol-2Al aluminate complex salt was added, 0.5 phr of dispersed magnesium oxide (Kyowamag 150; manufactured by Kyowa Chemical Industry Co., Ltd.) was added, then, by adding water and a 10% KOH solution, the pH was adjusted to 9.6 and the concentration was adjusted to 30%, and the latex liquid was left for one day.

(113) Next, NBRs used in Example 5 and Example 6 described below are 6338 manufactured by Synthomer.

Example 5

(114) A compound latex was prepared by adding 0.3 parts in terms of Al.sub.2O.sub.3 of the carbon dioxide-neutralized product of the sorbitol-4Al aluminate complex salt (water-soluble) and further adding 1.4 parts of 5% polyvinyl alcohol (PVA-117; manufactured by KURARAY CO., LTD.). By adding water and a 10% KOH solution to the compound liquid, the pH was adjusted to 9.5 and the latex concentration was adjusted to 30%.

(115) The above compound liquid was offered to a pot life test separately.

Example 6

(116) A PVA-110 (manufactured by KURARAY CO., LTD.) 7% solution was prepared, and a powder sodium aluminate 15% solution (in terms of Al.sub.2O.sub.3) was added such that one Al is bonded per six vinyl alcohol residues, so that a PVA-110 aluminate complex salt solution (abbreviated as PVA-110×6Al) was synthesized.

(117) A compound latex was prepared by directly adding 0.3 parts (in terms of Al.sub.2O.sub.3) of the above PVA-110×6Al solution to a NBR latex and further adding 1.0 part of a sizing agent (BANDIS T-25K; disproportionation rosin, manufactured by Harima Chemicals Group, Inc.). Then, by adding water and a 10% KOH solution, the pH was adjusted to 9.7 and the latex concentration was adjusted to 30%.

(118) 6. Manufacture of Dip Molded Articles (Fingerstalls)

(119) Manufacture of Dip Molded Articles (Fingerstalls)

(120) Mold sandblasted test tube by sandblasting (diameter 17 mm)

(121) Coagulant Liquid calcium nitrate tetrahydrate 300 g/L (Example 1 and Example 2) 200 g/L (Comparative Example 1, Examples 3, 4, 5, and 6)

(122) Dipping of Mold into Coagulant Liquid dipping time 10 seconds

(123) Film Deposition dipping of mold into latex prepared liquid described above, time 10 seconds deposition preliminary drying 75° C., 3 minutes washing (reaching) 50° C., 3 minutes deposition drying/heating 95° C., 3 minutes, 120° C., 15 minutes

(124) The fingerstalls were removed from the mold and used as samples of the following evaluation test.

(125) The pot lives of the above latex compounds and evaluation results of the dip molded articles are shown in Table 1.

(126) 1) Coagulant Agent Concentration

(127) (Result)

(128) By using the latex to which colloidal magnesium hydroxide is added (Example 3) and the latex to which magnesium oxide is added (Example 4), fingerstalls having thicknesses substantially the same as in the sulfur vulcanization latex to which zinc oxide is added (Comparative Example 1) can be manufactured at the same coagulant agent concentration. Moreover, by also using the latex to which PVA is added (Example 5) and the latex to which a PVA crosslinking agent is added (Example 6), fingerstalls can be manufactured at the same coagulant agent concentration as in the latex to which zinc oxide is added.

(129) 2) Physical Property Test

(130) (Result)

(131) Erythritol-2Al aluminate complex salt neutralized product NBR fingerstalls, erythritol-4Al aluminate complex salt directly-added NBR fingerstalls, sulfur vulcanization NBR fingerstalls, and commercial natural rubber gloves all showed tensile stresses of around 30 MPa. However, while the fracture elongation was about 600% in the sulfur vulcanization NBR, the fracture elongations in the aluminate complex salt-based fingerstalls reached 750-800%, which was the same as the fracture elongation of the natural rubber gloves, and extremely soft dipped rubber products could be obtained.

(132) Although Examples 5 and 6 are different in the latex manufacturer, substantially the same fingerstalls could be obtained.

(133) 3) Durability and Water Resistance Test

(134) After wearing the above fingerstalls on fingers successively for 14 days, a wearing aptitude test of durability, creep resistance, and water resistance was performed. The durability was classified into excellent, good, and normal by successively wearing on fingers and comprehensively judging the degree of swelling and the degree of whitening of the fingerstalls after wearing. The creep resistance was determined by the degree of an elongation (swelling) of the fingerstalls after wearing. The creep resistance was classified into excellent, good, and normal in ascending order of the degree of swelling. The water resistance was determined by the degree of whitening of a rubber film in wearing. Severe whitening was indicated as poor. The water resistance was classified into excellent, good, and normal corresponding to the degree of whitening.

(135) (Result)

(136) The durability, creep resistance, and water resistance of the erythritol-2Al aluminate complex salt neutralized product-added NBR latex fingerstalls (Example 1), the erythritol-4Al aluminate complex salt directly-added fingerstalls (Example 2), the colloidal magnesium hydroxide-added fingerstalls (Example 3), and the magnesium oxide-added fingerstalls (Example 4) have quality equal to or more than that of the sulfur vulcanization fingerstalls (Comparative Example 1).

(137) In Example 5 and Example 6, despite a different latex raw material, fingerstalls having the same quality as that of Examples described above could be manufactured.

(138) Non-Adherence Property Test

(139) Four manufactured fingerstalls were stacked alternately and sandwiched by a bulky book (Kojien). The fingerstalls were taken out three days later, and the non-adherence property was indicated as excellent when the fingerstalls were easily peeled.

(140) (Result)

(141) The fingerstalls manufactured from the latex obtained by blending PVA into the aluminate complex salt-based crosslinking agent and the latex obtained by blending the sizing agent into the PVA aluminate complex salt-based crosslinking agent were excellent in the non-adherence property.

(142) TABLE-US-00001 TABLE 1 NBR Fingerstalls or Natural Rubber Latex Gloves Latex Compound Tensile Non- Blending Pot Thickness Strength Elongation Creep Water Adherence Stability Life (mm) (MPa) (%) Durability Resistance Resistance Property Reference 0.08 mm 31.2 MPa 630% normal normal normal Example Latex Gloves Comparative no ≥60 days 0.1 mm 30.2 MPa 600% normal normal normal Example 1 aggregation Example 1 no ≥60 days 0.094 mm 30.5 MPa 810% excellent good good aggregation Example 2 no ≥60 days 0.095 mm 31.8 MPa 790% excellent excellent excellent aggregation Example 3 no ≥60 days 0.098 mm 29.8 MPa 780% excellent excellent excellent aggregation Example 4 no ≥60 days 0.098 mm 30.0 MPa 770% excellent excellent excellent aggregation Example 5 no ≥60 days 0.096 mm 26.9 MPa 710% excellent excellent excellent excellent aggregation Example 6 no ≥60 days 0.095 mm 27.5 MPa 700% excellent excellent excellent excellent aggregation

(143) (Evaluation)

(144) An NBR latex compound in which a neutralized product of an aluminate complex salt is blended and a latex compound into which an aluminate complex salt is directly blended to be neutralized can be easily prepared and have excellent pot lives.

(145) Moreover, fingerstalls manufactured from the above NBR latex compound have a strength (tensile strength) comparable to that of NBR sulfur vulcanization dipped products (latex gloves).

(146) Furthermore, a big characteristic of the present products is being soft products having an elongation at the same level as that of natural rubber latex products. Moreover, another big characteristic is durability, creep resistance, and water resistance surpassing those of sulfur vulcanization products.

(147) Therefore, the present products have properties capable of being comparable to natural rubber products even in a medical field.