JP2015199917A - Polyisocyanate composition having low temperature storage stability, and method for producing the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyisocyanate composition containing a carbodiimide group and an uretonimine group, which has greatly improved storage stability at a low temperature and a low color number, and to provide a method for producing the same.SOLUTION: Provided is a polyisocyanate composition having excellent low temperature storage stability and a low color number, which is obtained by adding to MDI (A) having many components, the so-called isomers, a carbodiimidation catalyst (B), a photostabilizer (C), and an antioxidant (D), and heating the mixture to convert NCO groups to carbodiimide and uretonimine. Also provided is a method for producing the same.

Description

  The present invention relates to a polyisocyanate composition containing a carbodiimide group and a uretonimine group, and a method for producing the same. More specifically, the present invention relates to a polyisocyanate composition having a low color number with greatly improved low-temperature storage stability and a method for producing the same.

A so-called carbodiimide-modified liquid MDI (hereinafter abbreviated as liquid MDI), which is modified with diphenylmethane diisocyanate (hereinafter abbreviated as MDI) and contains a carbodiimide group and / or uretonimine group, is a paint, a thermosetting elastomer, a potting material, and a foam. It is used as a raw material.
When stored at a low temperature in winter, 4,4′-MDI crystals, which are the main component, are precipitated in a few days, making it difficult to use. As countermeasures, heat retention during transportation and storage, heat melting during use, and the like have been performed, but there have been problems such as an increase in heat retention and heating costs and an increase in the number of processes.
In such a background, Patent Document 1 discloses, as a polyisocyanate composition excellent in low-temperature storage stability, constituents of a polyisocyanate composition including those having an isocyanate group carbodiimidized as 2, 2 A polyisocyanate composition obtained by carbodiimidizing a part of MDI, wherein the sum of '-MDI and 2,4'-MDI is 10 to 50% by weight and 4,4'-MDI is 90 to 50% by weight Although information is disclosed, it is storage stability at −5 ° C., and is not assumed to be used in cold regions of −10 ° C. and −20 ° C. considering practical use.
Moreover, in patent document 1, as a polyisocyanate composition excellent in low-temperature storage stability, the structural component of the polyisocyanate composition including the thing in which the isocyanate group was carbodiimidized is 2,2'-MDI and 2,4. When the total amount of '-MDI is more than 50% by weight and 4,4'-MDI is less than 50% by weight, coloring during the carbodiimidization reaction is increased, and the use application as a urethane product raw material is limited. The problem is not solved.

Japanese Patent Laid-Open No. 10-036470

  Even when used in a cold area of -20 ° C, it shows sufficient storage stability for a long period of time without considering the storage method, and when used in the above applications, it exhibits the same performance as conventional liquid MDI. The purpose was to provide a new liquid MDI with a low color number.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

That is, the present invention includes the following (1) to (7).
(1) containing polyisocyanate (A), carbodiimidization catalyst (B), light stabilizer (C), and antioxidant (D),
Structural unit (x) derived from 2,2′-diphenylmethane diisocyanate (a1), structural unit (y) derived from 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate (a3) The structural unit (z) derived from (x), (y), and (z) as a weight ratio of (x + y) :( z) = 40: 60 to 95: 5,
Containing at least one selected from the group consisting of a carbodiimide group-containing modified isocyanate and a uretonimine group-containing modified isocyanate, and APHA NO. The low-temperature storage-stable polyisocyanate composition characterized by having a color number of 200 or less.
(2) Structural unit (x) derived from 2,2′-diphenylmethane diisocyanate (a1), structural unit (y) derived from 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate The structural unit (z) derived from (a3) is included in the range of (x + y) :( z) = 51: 49 to 85:15 as the weight ratio of (x) and (y) to (z). (2) The low-temperature storage-stable polyisocyanate composition according to (1).
(3) Structural unit (x) derived from 2,2′-diphenylmethane diisocyanate (a1), structural unit (y) derived from 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate The structural unit (z) derived from (a3) is included in the range of (x + y) :( z) = 51: 49 to 75:25 as the weight ratio of (x) and (y) to (z). (2) The low-temperature storage-stable polyisocyanate composition according to (1).
(4) The low-temperature storage-stable polyisocyanate composition according to any one of (1) to (3), wherein the carbodiimidization catalyst (B) is a phospholene catalyst.
(5) The light stabilizer (C) is a hindered amine light stabilizer, and the antioxidant (D) is a phosphite antioxidant, wherein the light stabilizer (C) is a phosphite antioxidant. A low temperature storage stable polyisocyanate composition.
(6) Diphenylmethane diisocyanate (A) is subjected to a carbodiimidization reaction in the presence of a carbodiimidization catalyst (B), a light stabilizer (C), and an antioxidant (D) to synthesize a carbodiimide group-containing modified isocyanate. A method for producing a low-temperature storage-stable polyisocyanate composition according to any one of (1) to (5),
Diphenylmethane diisocyanate (A) is composed of 2,2′-diphenylmethane diisocyanate (a1), 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate (a3), (a1) and A method wherein the weight ratio of (a2) to (a3) is in the range of (a1 + a2) :( a3) = 40: 60 to 95: 5.
(7) A method for producing a low-temperature storage-stable polyisocyanate composition according to any one of (1) to (5), comprising synthesizing a modified isocyanate containing a uretonimine group, the carbodiimide obtained in (6) A process comprising producing a uretonimine group-containing modified isocyanate by uretonimineization of a group-containing modified isocyanate by aging.

  The liquid MDI of the present invention is stored at a low temperature for a long period of time that could not be obtained by the conventional liquid MDI without considering the storage method in particular for storage in a cold region at −10 ° C. and −20 ° C. Excellent results are exhibited, and there is little coloring during the carbodiimidization reaction, and the use as a urethane product raw material can be used without limitation.

Precipitation days when stored at -20 ° C

The present invention will be described in further detail.
The outline of the industrial production method of diphenylmethane diisocyanate (MDI) used in the present application is shown by the following three-stage process. (1) A polyamine containing diaminodiphenylmethane as a main component is obtained by a condensation reaction between aniline and formaldehyde. (2) By reacting this polyamine with phosgene, a crude MDI mainly composed of MDI is obtained. (3) MDI is obtained from the crude MDI by fractional distillation.

  Therefore, the isomer distribution of MDI is determined by the first stage condensation reaction. In this condensation reaction, a binuclear body, a trinuclear body, and a polynuclear body are generated. The dinuclear body has two benzene rings in one molecule obtained by reacting 2 moles of aniline and 1 mole of formaldehyde, and the trinuclear body has 3 moles of aniline and 2 moles of formaldehyde. The polynuclear substance is one having four or more benzene rings in one molecule.

  In the binuclear body, the 4,4′-isomer bonded at the para-para position is most produced, followed by the 2,4′-isomer bonded at the para-ortho position, and the least produced is ortho. -The 2,2'-isomer linked in the ortho position. These ratios can be easily controlled by changing the condensation temperature and the amount of catalyst. Since the isomer distribution is not changed by the second stage phosgenation reaction and the third stage fractionation, 4,4′-MDI is the most commonly obtained isomer of MDI and is commercially available. Many MDIs have a 4,4′-MDI content of 98% or more.

  The MDI (A) used in the present invention is composed of 2,2′-MDI (a1), 2,4′-MDI (a2) and 4,4′-MDI (a3), and (a1) and (a2 ) And (a3) are in the range of (a1 + a2) :( a3) = 40: 60 to 95: 5, and the carbodiimide group-containing modified isocyanate and / or uretonimine group-containing modified isocyanate in the polyisocyanate composition. It is characterized by containing. The weight ratio between the structural unit (x) derived from (a1) and the structural unit (y) derived from (a2) and the structural unit (z) derived from (a3) is the above (a1), ( This corresponds to the weight ratio of a2) and (a3).

  A well-known thing can be used as a carbodiimidization catalyst (B) used for this invention. Examples of the carbodiimidization catalyst include alkyl phosphates and phospholenes.

  Alkyl phosphate carbodiimidization catalysts include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate, trioctyl phosphate, triphenyl phosphate, tris (β-chloroethyl) phosphate, tris (β- Chloropropyl) phosphate, phosphoric acid dimethyl ester, phosphoric acid diethyl ester, phosphoric acid dipropyl ester, phosphoric acid butyl ester, phosphoric acid di (2-ethylhexyl) ester, phosphoric acid dioctyl ester, phosphoric acid monomethyl ester, phosphoric acid mono Ethyl ester, phosphoric acid monopropyl ester, phosphoric acid monobutyl ester, phosphoric acid mono (2-ethylhexyl) ester, phosphoric acid monooctyl ester, and In particular, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate, dimethyl phosphate, diethyl phosphate, phosphorus, etc. Acid dibutyl ester, phosphoric acid di (2-ethylhexyl) ester and the like are preferable.

  Examples of the phospholene carbodiimidization catalyst include 1-phenyl-3-methyl-3-phospholen-1-oxide, 1-methyl-3-methyl-3-phospholen-1-oxide, 1-ethyl-3-methyl-3- Phosphorene-1-oxide, 1-butyl-3-methyl-3-phospholene-1-oxide, 1- (N-piperidinyl) -3-methyl-3-phospholene-1-oxide, 1-morpholino-3-methyl- 3-phospholene-1-oxide, 1-phenyl-3-methyl-2-phospholene-1-oxide, 1-methyl-3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2- Phospholene-1-oxide, 1-butyl-3-methyl-2-phospholene-1-oxide, 1-phenoxy-3-methyl-2-phosphole -1-oxide, 1-phenyl-3-phospholene-1-oxide, 1-methyl-3-phospholene-1-oxide, 1-ethyl-3-phospholene-1-oxide, 1-phenyl-2-phospholene-1 -Oxide, 1-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 1-phenyl-3-methyl-3-phospholene-1-sulfide, and mixtures thereof It is done. Of these, 1-phenyl-3-methyl-3-phospholene-1-oxide, 1-phenyl-3-methyl-2-phospholene-1-oxide, 1-phenyl-3-phospholene 1-oxide, 1-phenyl-2-phospholene-1-oxide and the like are preferable.

  In the selection of alkylphosphate and phospholene catalysts, the catalyst activity is strong, the reaction at low temperature is possible, and a liquid MDI with a low color number can be obtained. A phospholene catalyst is preferable because it can be used.

  Known light stabilizers, antioxidants, and ultraviolet absorbers used in the present invention can be used. Examples of the light stabilizer include hindered amines, examples of the antioxidant include hindered phenols and phosphites, and examples of the ultraviolet absorber include benzotriazoles.

  Examples of hindered amine light stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, and bis (1 -Undecanoxyl-2,2,6,6-tetramethylpiperidin-4-yl) carboxyl, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4 Piperidyl methacrylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, tetrakis (2,2,6,6-tetramethyl-4 -Piperidyl) butane-1,2,3,4-tetracarboxylate, and mixtures thereof. Among these, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate are preferable.

  As the hindered phenol-based and phosphite-based antioxidants, 1,3,5-tris (3,5-di-t-butyl-4-hydroxylbenzyl) -1,3,5-triazine-2,4, 6 (1H, 3H, 5H) -trione, 4,4,4- (1-methylpropanyl-3-ylidene) tris (6-t-butyl-m-cresol), 6,6′-di-t- Butyl-4,4′-butylidene-di-m-cresol, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- (3,5-di- t-butyl-4-hydroxyphenyl) propionate], 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxyphenylmethyl) -2,4,6- Trimethylbenzene, 2,6-di-t-butyl-p-cresol, triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, tris (2-ethylhexyl) phosphite, tridecylphos Phyto, trilauryl phosphite, tris (tridecyl) phosphite, trioleyl phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono (tridecyl) phosphite, trilauryl trithiophosphite, tetra Phenyldipropylene glycol Diphosphite, tetraphenyl (tetratridecyl) pentaerythritol tetraphosphite, tetra (C12-C15 alkyl) -4,4'-isopropylidene diphenyl phosphite, bis (tridecyl) pentaerythritol diphosphite, bis (nonylphenyl) Pentaerythritol diphosphite, bis (decyl) pentaerythritol diphosphite, tristearyl phosphite, distearyl pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite, hydrogenated bisphenol A Examples include pentaerythritol phosphite polymer, water-added bisphenol A phosphite polymer, and mixtures thereof. Among these, 2,6-di-t-butyl-p-cresol, triphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, pentaerythritol tetrakis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate] is preferred.

  Examples of the benzotriazole antioxidant include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5 Chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2,2 '-Methylenebis [6- (2H-benzotriazol-2-yl) -4-t-octylphenol], 6- (2-benzotriazolyl-4-t-octyl-6'-t-butyl-4'- Examples include methyl-2,2′-methylenebisphenol and mixtures thereof.

  The conditions of the carbodiimidated ureton iminization reaction in the present invention are greatly different between the phospholene catalyst and the alkyl phosphate catalyst.

  When using a phospholene-based catalyst, 0.1 to 50 ppm, preferably 0.1 to 10 ppm of catalyst is added to the MDI composition and heated to 70 to 150 ° C, preferably 80 to 120 ° C. Allow the reaction to proceed. The progress of the reaction is confirmed from time to time by measuring the content of residual isocyanate groups (hereinafter abbreviated as NCO groups) in the reaction system. The NCO groups are 4.76 to 7.62 mmol / g, preferably 5.48 to 7 When reaching 38 mmol / g, the reaction is stopped by at least one of cooling and addition of an acid-based reaction terminator.

  The above acid-based reaction terminators include hydrogen chloride, nitric acid, sulfuric acid, phosphoric acid, acetic acid, benzoic acid, phthalic acid, benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid, aluminum trichloride, boron trifluoride, three Examples thereof include boron chloride, iron trifluoride, iron trichloride, trichlorosilane, diphenyltrichlorosilane, diphenyldichlorosilane, and mixtures thereof. More preferably, phosphoric acid, benzenesulfonic acid, toluenesulfonic acid, and naphthalenesulfone. Acids, boron trifluoride, boron trichloride, iron trifluoride, iron trichloride, diphenyldichlorosilane, and mixtures thereof.

  When an alkyl phosphate catalyst is used, the catalyst is added in an amount of 0.05 to 5.00% by weight, preferably 0.1 to 2% by weight, and 150 to 250 ° C., preferably 180%, based on the MDI composition. The reaction is allowed to proceed by heating to from ˜230 ° C. The progress of the reaction is confirmed from time to time by measuring the residual NCO group content in the reaction system, and when the NCO group reaches 4.76 to 7.62 mmol / g, preferably 5.48 to 7.38 mmol / g, cooling is performed. To stop the reaction.

  When the residual NCO group content after the carbodiimidization reaction is less than 4.76 mmol / g, the increase in viscosity due to an increase in the polymer is remarkably unsuitable for practical use from the viewpoint of workability. On the other hand, when the NCO group exceeds 7.62 mmol / g, the low-temperature storage stability of the polyisocyanate composition becomes poor, and physical properties expected for coating films, elastomers, foams and the like using the polyisocyanate composition as a raw material do not appear.

  Both the liquid MDI using a phospholene catalyst and the liquid MDI using an alkyl phosphate catalyst can be used after stopping the carbodiimidization reaction. However, after the reaction is stopped, the carbodiimide group is uretonimine by aging. Those based can also be used. Aging is performed at 15 to 70 ° C., preferably 30 to 60 ° C. as aging conditions. By uretonimination, a polyisocyanate composition having a stable NCO group content with time can be obtained. The NCO content of the polyisocyanate composition after aging (ureton iminization) is 4.52 to 7.38 mmol / g, preferably 5.24 to 7.14 mmol / g.

  Liquid MDI that has been manufactured and prepared generally contains 0.1 to 3% by weight of an MDI dimer (hereinafter abbreviated as MDI dimer) as a by-product. It contains a similar amount of MDI dimer. Depending on the reaction conditions, the amount of MDI dimer more than the solubility in liquid MDI may be generated, resulting in turbidity. In this case, transparent liquid MDI can be obtained by filtration.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition, the part in an example shows a weight part and% shows weight%, respectively.

[Preparation of MDI with various isomer mixing ratios]
Preparation Example 1
In a reaction apparatus comprising a stirrer, a thermometer, a cooling pipe, and a nitrogen gas introduction pipe, the total of 2,2′-MDI (a1) and 2,4′-MDI (a2) is 95% by weight, 4,4′- 220 parts of MDI (hereinafter abbreviated as MDI-95) with 5% by weight of MDI (a3), and the total of 2,2′-MDI (a1) and 2,4′-MDI (a2) is 1% by weight, 4 , 4′-MDI (a3) is mixed with 1780 parts of 99% by weight of MDI (hereinafter abbreviated as MDI-1), stirred at 50 ° C. for 10 minutes, and 2,2′-MDI and 2,4′- An MDI with a total of 12% by weight of MDI and 88% by weight of 4,4′-MDI was prepared. This MDI is referred to as MDI-12. The weights of (a1), (a2), and (a3) are derived from the structural units (x) and (a2) derived from (a1) and (a3). It corresponds to the weight of the structural unit (z). The same applies to the following preparation examples.

Preparation Example 2
405 parts of MDI-95 and 1595 parts of MDI-1 were mixed in the same reactor as in Preparation Example 1, and stirred at 50 ° C. for 10 minutes. The total of 2,2′-MDI and 2,4′-MDI 20% by weight and 4,4′-MDI was 80% by weight MDI. This MDI is referred to as MDI-20.

Preparation Example 3
In the same reactor as in Preparation Example 1, 830 parts of MDI-95 and 1170 parts of MDI-1 were mixed, stirred at 50 ° C. for 10 minutes, and the total of 2,2′-MDI and 2,4′-MDI. Prepared 40% by weight and 4,4′-MDI 60% by weight. This MDI is referred to as MDI-40.

Preparation Example 4
In the same reactor as in Preparation Example 1, 1060 parts of MDI-95 and 940 parts of MDI-1 were mixed, stirred at 50 ° C. for 10 minutes, and the total of 2,2′-MDI and 2,4′-MDI Was prepared, and 51% by weight of 4,4′-MDI was 49% by weight. This MDI is referred to as MDI-51.

Preparation Example 5
In the same reactor as in Preparation Example 1, 1150 parts of MDI-95 and 850 parts of MDI-1 were mixed, stirred at 50 ° C. for 10 minutes, and the total of 2,2′-MDI and 2,4′-MDI Of 55% by weight and 4,4'-MDI of 45% by weight were prepared. This MDI is referred to as MDI-55.

Preparation Example 6
In the same reactor as in Preparation Example 1, 1360 parts of MDI-95 and 640 parts of MDI-1 were mixed, stirred at 50 ° C. for 10 minutes, and the total of 2,2′-MDI and 2,4′-MDI Was prepared, and 65% by weight and 4,4′-MDI was 35% by weight. This MDI is referred to as MDI-65.

Preparation Example 7
In the same reactor as in Preparation Example 1, 1580 parts of MDI-95 and 420 parts of MDI-1 were mixed, stirred at 50 ° C. for 10 minutes, and the total of 2,2′-MDI and 2,4′-MDI. Prepared 75% by weight and 4,4′-MDI 25% by weight. This MDI is referred to as MDI-75.

Preparation Example 8
In the same reaction apparatus as in Preparation Example 1, 1790 parts of MDI-95 and 210 parts of MDI-1 were mixed, stirred at 50 ° C. for 10 minutes, and the total of 2,2′-MDI and 2,4′-MDI. Was 85% by weight and 4,4′-MDI was 15% by weight. This MDI is referred to as MDI-85.

Preparation Example 9
2000 parts of MDI-95 was added to the same reactor as in Preparation Example 1, and the total of 2,2′-MDI and 2,4′-MDI was 95% by weight, and 4,4′-MDI was 5% by weight. Was prepared. This MDI is referred to as MDI-95.
Preparation Examples 1 to 9 are shown in Tables 1 and 2.

In Table 1, the isomer ratio of MDI was measured according to JISK-0114-1982-8.2.
* GC-9AM (TCD) manufactured by Shimadzu Corporation was used for the gas chromatograph, and diphenylmethane was used for the internal standard substance.

Example 1: Production of liquid MDI- (1) consisting of 2,2′-MDI + 2,4′-MDI = 40%
In a reactor equipped with a stirrer, a thermometer, an Allen cooling pipe and a nitrogen gas introduction pipe, 2000 parts of MDI-40 as the MDI composition (A) and bis (1,2,2) as the hindered amine light stabilizer (C) , 6,6-pentamethyl-4-piperidyl) sebacate (hereinafter abbreviated as BPPS), and tris (2,4-di-t-butylphenyl) phos as a phosphite antioxidant (D). 0.83 part of phyto (hereinafter abbreviated as TBP) is charged, and 0.004 part of 1-phenyl-3-methyl-3-phospholene-1-oxide (hereinafter abbreviated as PMPO) is charged as the carbodiimidization catalyst (B). While stirring, the temperature was raised to 95 ° C. to cause carbodiimidization reaction. When the NCO content reached 7.05 mmol / g, 0.2 part of paratoluenesulfonic acid (hereinafter abbreviated as PTSH) was added and the reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (1). The MDI content of the liquid MDI (1) was 6.95 mmol / g.

(Example 2: Production of liquid MDI- (2) comprising 2,2'-MDI + 2,4'-MDI = 51%)
A reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe is charged with 2000 parts of MDI-51 as an MDI composition (A) and 0.04 part of BPPS as a hindered amine light stabilizer (C). , 1.06 parts of TBP as a phosphite antioxidant (D) and 0.006 parts of PMPO as a carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause a carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.3 part of PTSH was added, and the whole reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (2). The MDI content of the liquid MDI (2) was 6.82 mmol / g.

(Example 3: Production of liquid MDI- (3) comprising 2,2'-MDI + 2,4'-MDI = 55%)
A reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe is charged with 2000 parts of MDI-55 as an MDI composition (A) and 0.04 part of BPPS as a hindered amine light stabilizer (C). , 1.15 parts of TBP as phosphite antioxidant (D) and 0.006 parts of PMPO as carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.3 part of PTSH was added, and the whole reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (3). The MDI content of the liquid MDI (3) was 6.94 mmol / g.

(Example 4: Production of liquid MDI- (4) comprising 2,2'-MDI + 2,4'-MDI = 65%)
A reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe is charged with 2000 parts of MDI-65 as the MDI composition (A) and 0.04 part of BPPS as the hindered amine light stabilizer (C). , 1.36 parts of TBP as phosphite antioxidant (D) and 0.006 parts of PMPO as carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.3 part of PTSH was added, and the whole reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (4). The MDI content of the liquid MDI (4) was 6.91 mmol / g.

(Example 5: Production of liquid MDI- (5) comprising 2,2′-MDI + 2,4′-MDI = 75%)
A reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe is charged with 2000 parts of MDI-75 as an MDI composition (A) and 0.04 part of BPPS as a hindered amine light stabilizer (C). , 1.58 parts of TBP as phosphite antioxidant (D) and 0.006 parts of PMPO as carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.3 part of PTSH was added, and the whole reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (5). The MDI content of the liquid MDI (5) was 6.87 mmol / g.

(Example 6: Production of liquid MDI- (6) comprising 2,2′-MDI + 2,4′-MDI = 85%)
A reactor equipped with a stirrer, thermometer, allene cooling pipe, and nitrogen gas introduction pipe is charged with 2000 parts of MDI-85 as the MDI composition (A) and 0.04 part of BPPS as the hindered amine light stabilizer (C). , 1.79 parts of TBP as a phosphite antioxidant (D) and 0.006 parts of PMPO as a carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.3 part of PTSH was added, and the whole reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (6). The MDI content of the liquid MDI (6) was 6.85 mmol / g.

(Example 7: Production of liquid MDI- (7) comprising 2,2′-MDI + 2,4′-MDI = 95%)
A reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe is charged with 2000 parts of MDI-95 as the MDI composition (A) and 0.04 part of BPPS as the hindered amine light stabilizer (C). , 2.00 parts of TBP as a phosphite antioxidant (D) and 0.006 parts of PMPO as a carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause a carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.3 part of PTSH was added, and the whole reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (7). The MDI content of the liquid MDI (7) was 6.84 mmol / g.

(Comparative Example 1: Production of liquid MDI- (ratio 1) consisting of 2,2'-MDI + 2,4'-MDI = 12%)
A reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe is charged with 2000 parts of MDI-12 as the MDI composition (A) and 0.04 part of BPPS as the hindered amine light stabilizer (C). , 0.22 parts of TBP as phosphite antioxidant (D) and 0.004 parts of PMPO as carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.2 part of PTSH was added and the reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (ratio 1). The MDI content of the liquid MDI (ratio 1) was 6.98 mmol / g.

(Comparative Example 2: Production of liquid MDI- (ratio 2) consisting of 2,2'-MDI + 2,4'-MDI = 20%)
A reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe is charged with 2000 parts of MDI-20 as the MDI composition (A) and 0.04 parts of BPPS as the hindered amine light stabilizer (C). , 0.40 parts of TBP as phosphite antioxidant (D) and 0.004 parts of PMPO as carbodiimidization catalyst (B) were added, and the temperature was raised to 95 ° C. with stirring to cause carbodiimidization reaction. It was. When the NCO content reached 7.05 mmol / g, 0.2 part of PTSH was added and the reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (ratio 2). The MDI content of the liquid MDI (ratio 2) was 6.90 mmol / g.

(Comparative Example 3: Production of liquid MDI- (ratio 3) consisting of 2,2'-MDI + 2,4'-MDI = 40%)
In a reactor equipped with a stirrer, a thermometer, an Allen cooling pipe, and a nitrogen gas introduction pipe, 2000 parts of MDI-40 as an MDI composition (A), a hindered amine light stabilizer (C) and a phosphite antioxidant ( D) was not used, and 0.004 part of PMPO was charged as a carbodiimidization catalyst (B), and the temperature was raised to 95 ° C. while stirring to cause carbodiimidization reaction. When the NCO content reached 7.05 mmol / g, 0.2 part of PTSH was added and the reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (ratio 3). The MDI content of the liquid MDI (ratio 3) was 6.95 mmol / g.

(Comparative Example 4: Production of liquid MDI- (ratio 4) consisting of 2,2'-MDI + 2,4'-MDI = 95%)
In a reactor equipped with a stirrer, a thermometer, an allene cooling pipe, and a nitrogen gas introduction pipe, 2000 parts of MDI-95 as an MDI composition (A), a hindered amine light stabilizer (C) and a phosphite antioxidant ( D) was not used, and 0.006 part of PMPO was charged as a carbodiimidization catalyst (B), and the temperature was raised to 95 ° C. while stirring to cause carbodiimidization reaction. When the NCO content reached 7.05 mmol / g, 0.3 part of PTSH was added, and the whole reactor was air-cooled to 45 ° C. to stop the carbodiimidization reaction. Thereafter, the mixture was kept at 45 ° C. for 20 hours to convert the carbodiimide group to a uretonimine group, then cooled to 25 ° C., and filtered to obtain liquid MDI (ratio 4). The MDI content of the liquid MDI (ratio 4) was 6.84 mmol / g.

  Tables 3 to 4 collectively describe examples and comparative examples.

In Table 3 to Table 4,
BPPS: bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate TBP: tris (2,4-di-t-butylphenyl) phosphite PMPO: 1-phenyl-3-methyl-3- Phosphorene-1-oxide PTSH: p-toluenesulfonic acid * NCO group content: In accordance with JIS K1603-1985-5.3.

(Storage stability test method)
The liquid MDI obtained in Examples 1 to 7 and Comparative Examples 1 to 4 was placed in a 200 ml sample bottle, and a storage stability test was performed at −5 ° C., −10 ° C., and −20 ° C. The change with time was visually observed, and the precipitation of crystals was observed on a daily basis.

(Color number test)
The liquid MDI obtained in Examples 1 to 7 and Comparative Examples 1 to 4 was placed in a 200 ml sample bottle, and the color number was evaluated by comparing with a color number standard sample. As a unit, APHA No. Was used.

  In Comparative Examples 1 and 2 in Table 6, precipitation was confirmed at −10 ° C. within 10 days and at −20 ° C. within 5 days, while Examples 1 to 7 in Table 5 were −10 ° C. No precipitation was confirmed for 14 days at −20 ° C. for 64 days, which proved advantageous for storage and use in winter and cold regions.

  In Comparative Examples 3 and 4 in Table 6, since BPPS was not used as the light stabilizer and TBP was not used as the antioxidant, the number of colors was APHA No. In contrast to the poor 250 and 500, Examples 1 and 7 having the same isomer ratio used BPPS as the light stabilizer and TBP as the antioxidant. It turns out that it is improving with 50 and 150.

  As shown in Examples 1 to 7, the liquid MDI of the present invention can be obtained by conventional liquid MDI without considering the storage method in particular for storage in a cold region at −10 ° C. and −20 ° C. It was confirmed that excellent results were obtained by storage at low temperatures over a long period of time, and there was little coloration during the carbodiimidization reaction, and it could be used without being limited to the intended use as a raw material for urethane products.

Claims (7)

Including a polyisocyanate (A), a carbodiimidization catalyst (B), a light stabilizer (C), and an antioxidant (D);
Structural unit (x) derived from 2,2′-diphenylmethane diisocyanate (a1), structural unit (y) derived from 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate (a3) The structural unit (z) derived from (x), (y), and (z) as a weight ratio of (x + y) :( z) = 40: 60 to 95: 5,
Containing at least one selected from the group consisting of a carbodiimide group-containing modified isocyanate and a uretonimine group-containing modified isocyanate, and APHA NO. The low-temperature storage-stable polyisocyanate composition characterized by having a color number of 200 or less. Structural unit (x) derived from 2,2′-diphenylmethane diisocyanate (a1), structural unit (y) derived from 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate (a3) (X), (y), and (z) as a weight ratio of (x + y) :( z) = 51: 49 to 85:15 The low-temperature storage-stable polyisocyanate composition according to claim 1. Structural unit (x) derived from 2,2′-diphenylmethane diisocyanate (a1), structural unit (y) derived from 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate (a3) The structural unit (z) derived from is included in the range of (x + y) :( z) = 51: 49 to 75:25 as a weight ratio of (x) and (y) to (z). The low-temperature storage-stable polyisocyanate composition according to claim 1. The low-temperature storage-stable polyisocyanate composition according to any one of claims 1 to 3, wherein the carbodiimidization catalyst (B) is a phospholene catalyst. The low temperature storage stability according to any one of claims 1 to 3, wherein the light stabilizer (C) is a hindered amine light stabilizer and the antioxidant (D) is a phosphite antioxidant. Polyisocyanate composition. A method comprising subjecting diphenylmethane diisocyanate (A) to a carbodiimidization reaction in the presence of a carbodiimidization catalyst (B), a light stabilizer (C), and an antioxidant (D) to synthesize a carbodiimide group-containing modified isocyanate. A method for producing a low-temperature storage-stable polyisocyanate composition according to any one of claims 1 to 5,
Diphenylmethane diisocyanate (A) is composed of 2,2′-diphenylmethane diisocyanate (a1), 2,4′-diphenylmethane diisocyanate (a2), and 4,4′-diphenylmethane diisocyanate (a3), and (a1) and A method wherein the weight ratio of (a2) to (a3) is in the range of (a1 + a2) :( a3) = 40: 60 to 95: 5. A method for producing a low-temperature storage-stable polyisocyanate composition according to any one of claims 1 to 5, comprising synthesizing a uretonimine group-containing modified isocyanate, and comprising the carbodiimide group-containing modification obtained in claim 6. A process comprising producing an uretonimine group-containing modified isocyanate by uretonimineization of an isocyanate by aging.

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