A method for preparing a polyurethane catalyst for rubber rolls using camphene as a starting material

Abstract

The application relates to a method for preparing a polyurethane catalyst for rubber rolls by using camphene as a starting material, and relates to a method for preparing a polyurethane catalyst for rubber rolls, wherein the polyurethane catalyst for rubber rolls is chemical formula 1, which is obtained by carbon-nitrogen coupling reaction of chemical formula 3 and chemical formula 4 prepared from camphene (chemical formula 2), wherein chemical formula 1, chemical formula 2 and chemical formula 3 (X is I, Br or Cl) are shown as follows; R1 and R2 are the same or different substituted aryl or heteroaryl.

Description

Technical Field

[0001] This invention relates to a method for preparing a polyurethane catalyst for rubber rollers, and more particularly to a method for preparing a polyurethane catalyst for rubber rollers using camphorene as a starting material. Background Technology

[0002] Polyurethane rollers have a wide range of applications, exhibiting excellent wear resistance, corrosion resistance, and elasticity, playing a vital role in various industries. In various mechanical equipment, they are used as complementary rollers for new materials. In the textile industry, they effectively solve the problem of yarn entanglement, thus greatly improving textile efficiency. Furthermore, polyurethane rollers are also found in the printing industry. Using polyurethane rollers not only meets the requirements of different printing presses but also makes the ink printing effect clearer, becoming an indispensable and powerful tool in the printing industry. Currently, polyurethane rollers are mainly obtained by casting polyisocyanates with polyester polyols, polyether polyols, or polycaprolactone under the action of a catalyst. Therefore, the catalyst is an important auxiliary agent in the preparation of cast polyurethane rollers.

[0003] Polyurethane catalysts can be broadly classified into two categories based on their chemical structure: metal alkyl compounds and tertiary amines. Metal alkyl compounds mainly include those made of bismuth, tin, titanium, antimony, mercury, and zinc. Tertiary amine catalysts can be further classified into aliphatic amines, alicyclic amines, aromatic amines, and alkanolamines, as well as their ammonium salts.

[0004] Alkyl compounds are lipid-soluble and more easily cross biological membranes than inorganic metals, being absorbed through the intestinal wall and entering the brain and placenta, thus exhibiting strong biotoxicity. Alkyl metal compounds can easily cause central nervous system disorders. In vivo, the microsomal drug metabolism enzyme system, primarily in organs such as the liver, removes alkyl and aromatic groups from organometallic compounds, ultimately transforming them into inorganic metals. For example, heavy metal catalysts such as butyltin, phenyltin, lead, and mercury are non-biodegradable, easily polluting the environment and harming human health. Organotin catalysts, in particular, have a median lethal dose (LD50) of 243 mg / kg, classifying them as moderately toxic compounds with significant human toxicity. Furthermore, these compounds readily undergo oxidative hydrolysis reactions with oxygen and water, easily reducing catalytic activity or even deactivating them in the production of waterborne polyurethanes, limiting their application. In recent years, various countries have increased restrictions on the use of organometallic catalysts. Since 2012, the European Union has raised its testing standards for organometallic catalysts; therefore, tertiary amine catalysts are a major direction for future polyurethane catalysis research.

[0005] Tertiary amine catalysts exhibit two main reactions in the synthesis of polyurethane, especially polyurethane foam: the reaction of -NCO with water and the reaction of -NCO with hydroxyl-terminated polyesters and polyether polyols. Both tertiary amine catalysts possess strong catalytic activity, particularly in the reaction of -NCO with -OH. The former promotes rapid polymer chain growth, a rapid increase in viscosity, and a rapid improvement in the strength of the foam network skeleton. The latter promotes the reaction of -NCO with water, rapidly generating carbon dioxide gas, causing the polymer to expand rapidly in volume.

[0006] There are many types of tertiary amine compounds used as catalysts for polyurethane. Based on their chemical structure, they can be basically divided into three categories: aliphatic amines, alicyclic amines, and aromatic amines. Among them, the most commonly used in the polyurethane industry are triethylenediamine, N-alkylmorpholine, and bis(2-methyloxyethyl) ether.

[0007] In tertiary amine compounds, the three hydrogen atoms of the amino group are replaced by electron-donating groups and alkyl groups with significant steric hindrance. While tertiary amines exhibit weaker basicity than primary and secondary amines due to various factors, their unique substituent structures on the nitrogen atom make them excellent catalysts for polyurethane synthesis. For example, N,N,N',N'-tetraethylmethylenediamine has a higher negative logarithm (pKa) dissociation constant than other catalysts, and is similar to triethylamine, but its catalytic activity is very low. The basicity (pKa) of amine catalysts is a result of electronic effects, meaning it is influenced by the electronic effects of substituents on the nitrogen atom. Electron-donating substituents will increase the pKa value of the amine, thus improving catalytic activity. However, the steric hindrance effect of the substituents must also be considered. A large steric hindrance effect will decrease catalytic activity. Although N,N,N',N'-tetraethylmethylenediamine has a high pKa value, its catalytic activity is significantly reduced due to the steric hindrance effect of the four large ethyl substituents on the nitrogen atom. In contrast, triethylamine is not only highly basic but also exhibits low steric hindrance, demonstrating strong catalytic activity. Triethylenediamine is a tertiary amine with a unique chemical structure. Its two nitrogen atoms are attached to three ethyl groups, forming a very compact and highly symmetrical bicyclic cage structure. Furthermore, the nitrogen atoms are not attached to any substituents, allowing the pair of empty electrons on the fully exposed nitrogen atoms to more easily approach the -NCO group, forming highly unstable complexes that strongly catalyze the reaction of isocyanates. It is currently one of the most important catalysts in the polyurethane industry.

[0008] According to JP2018090561A, in the preparation of tertiary aromatic amines of dibenzothiophene or dibenzofuran, 3-bromodibenzofuran or 3-bromodibenzothiophene is typically used as a starting material, reacting with an aryl primary amine to generate a diaryl secondary amine compound. This diaryl secondary amine compound then undergoes a nitrogen-based arylation reaction to form tertiary aromatic amines. However, on the one hand, 3-bromodibenzofuran or 3-bromodibenzothiophene is not only costly but also difficult to prepare, involving lengthy preparation steps and requiring highly hazardous operations such as nitration and hydrogenation. On the other hand, many aryl primary amine compounds are highly hazardous; for example, 4-aminobiphenyl, 1-naphthylamine, and 2-naphthylamine, commonly used in the preparation of tertiary aromatic amines in existing technologies, are all listed as Group 1 carcinogens by the WHO. These factors hinder the synthesis, research, and development of tertiary aromatic amines of dibenzothiophene or dibenzofuran with a 3-position substitution at the nitrogen atom.

[0009] In summary, the catalytic effect of tertiary amine catalysts is mainly due to their Lewis base properties, which promote the transfer of protons in hydroxyl groups, thereby accelerating the reaction between isocyanates and hydroxyl groups. However, current amine catalysts suffer from drawbacks such as high cost and the inability to simultaneously achieve catalytic efficiency and environmental safety. Summary of the Invention

[0010] The purpose of this invention is to provide a method for preparing polyurethane catalysts for rubber rollers using camphorene as a starting material. The camphorene-based polyurethane catalyst does not contain heavy metals, making it safer for the environment. It has a catalytic effect on the polymerization reaction of diisocyanate and diol, thus solving the technical problem of catalytic efficiency of polyurethane while taking into account environmental protection and safety.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A method for preparing a polyurethane catalyst for rubber rollers using camphorene as a starting material, wherein the catalyst is obtained by carbon-nitrogen coupling reaction of camphorene to obtain tertiary amine compounds with various structures, and one or more of these compounds are used as catalysts for curing polyurethane for rubber rollers.

[0013] The structural formula of the camphorene tertiary amine compound prepared from camphorene is shown in Figure 1.

[0014]

[0015] Camphorene tertiary amine chemical formula 1

[0016] Among them, R1 and R2 are the same or different substituted aryl or heteroaryl groups;

[0017] The preparation steps of the polyurethane catalyst for the rubber roller material are as follows:

[0018] (1) ;

[0019] Camphorene (chemical formula 2) Camphorene diamine (chemical formula 3)

[0020] (2)

[0021] Camphorene diamine haloaryl or heteroaryl compounds camphorene tertiary amine compounds chemical formula 1

[0022] Where X is I, Br, or Cl;

[0023] Camphorene tertiary amine compounds are synthesized by carbon-nitrogen coupling reaction of camphorene diamine and haloaryl or haloheteroaryl compounds.

[0024] The method for preparing a polyurethane catalyst for rubber rollers using camphorene as a starting material, wherein the camphorene diamine (chemical formula 3) is synthesized as a primary amine via a one-step metal-free catalytic hydrogenation amination of camphorene and ammonium carbonate; ammonium carbonate is used as the ammonia source for the primary amine, and the organic salt Mes-Acr-Ph is used. ＋ (E*red=+2.20 V) is used as a photocatalyst.

[0025] The method for preparing a polyurethane catalyst for rubber rollers using camphorene as a starting material, wherein R1 and R2 are each independently selected from the group consisting of the following substituents, the types of substituents being shown in 1-12:

[0026]

[0027]

[0028]

[0029] The method for preparing a polyurethane catalyst for rubber rollers using camphorene as a starting material, wherein the tertiary amine compound is a compound with the structure shown in 1 to 66:

[0030]

[0031] Tertiary amine compound 1, tertiary amine compound 2, tertiary amine compound 3

[0032]

[0033] Tertiary amine compound 4, tertiary amine compound 5, tertiary amine compound 6

[0034]

[0035] Tertiary amine compound 7, tertiary amine compound 8, tertiary amine compound 9

[0036]

[0037] Tertiary amine compound 10, tertiary amine compound 11, tertiary amine compound 12

[0038]

[0039] Tertiary amine compound 13, tertiary amine compound 14, tertiary amine compound 15

[0040]

[0041] Tertiary amine compound 16, tertiary amine compound 17, tertiary amine compound 18

[0042]

[0043] Tertiary amine compound 19, tertiary amine compound 20, tertiary amine compound 21

[0044]

[0045] Tertiary amine compound 22, tertiary amine compound 23, tertiary amine compound 24

[0046]

[0047] Tertiary amine compound 25, tertiary amine compound 26, tertiary amine compound 27

[0048]

[0049] Tertiary amine compound 28, tertiary amine compound 29, tertiary amine compound 30

[0050]

[0051] Tertiary amine compound 31, tertiary amine compound 32, tertiary amine compound 33

[0052]

[0053] Tertiary amine compound 34, tertiary amine compound 35, tertiary amine compound 36

[0054]

[0055] Tertiary amine compound 37, tertiary amine compound 38, tertiary amine compound 39

[0056]

[0057] Tertiary amine compound 40, tertiary amine compound 41, tertiary amine compound 42

[0058]

[0059] Tertiary amine compound 43, tertiary amine compound 44, tertiary amine compound 45

[0060]

[0061] Tertiary amine compound 49, tertiary amine compound 50, tertiary amine compound 51

[0062]

[0063] Tertiary amine compound 52, tertiary amine compound 53, tertiary amine compound 54

[0064]

[0065] Tertiary amine compound 55, tertiary amine compound 56, tertiary amine compound 57

[0066]

[0067] Tertiary amine compound 58, tertiary amine compound 59, tertiary amine compound 60

[0068]

[0069] Tertiary amine compound 61, tertiary amine compound 62, tertiary amine compound 63

[0070]

[0071] Tertiary amine compound 64, tertiary amine compound 65, tertiary amine compound 66

[0072] The advantages and effects of this invention are:

[0073] This invention uses camphorene, a natural compound, as a starting material, avoiding the use of highly toxic and environmentally polluting carcinogens such as 4-aminobiphenyl, 1-naphthylamine, and 2-naphthylamine. This significantly reduces harm to operators and environmental pollution, making the preparation process of tertiary amine catalysts safer and more environmentally friendly. Simultaneously, this process successfully avoids the use of expensive starting materials such as 3-bromodibenzofuran or 3-bromodibenzothiophene, thereby significantly reducing the preparation cost of tertiary amine catalysts. Therefore, the preparation process of the camphorene tertiary amine compound of this invention also has the advantage of low cost. Detailed Implementation

[0074] The present invention will now be described in detail with reference to the embodiments.

[0075] A polyurethane catalyst for rubber rollers is obtained by using camphorene as a raw material through a carbon-nitrogen coupling reaction to obtain tertiary amine compounds with various structures. One or more of these compounds can be used as catalysts for curing polyurethane for rubber rollers.

[0076] This invention provides a method for preparing a camphorene-based polyurethane catalyst, wherein the structure of the tertiary amine compound is shown in Chemical Formula 1:

[0077]

[0078] Chemical Formula 1

[0079] Wherein, R1 and R2 are the same or different substituted aryl or heteroaryl groups;

[0080] The preparation method of the polyurethane catalyst for the rubber roller material includes the following steps:

[0081] Step 1 ;

[0082] Camphorene (chemical formula 2) Camphorene diamine (chemical formula 3)

[0083] Step 2 ;

[0084] Camphorene diamine haloaryl or heteroaryl compounds camphorene tertiary amine compounds chemical formula 4

[0085] Where X is I, Br, or Cl;

[0086] Camphorene tertiary amine compounds are synthesized by carbon-nitrogen coupling reaction of camphorene diamine and haloaryl or haloheteroaryl compounds.

[0087] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments. Example 1

[0088] Synthesis of camphorene diamine

[0089] Under nitrogen protection, 98 g (1 mol) of camphorene, 30% mol of camphorene thiol, and 15% mol of camphorene Mes-Acr-Ph were added to a 250 mL reaction flask. + 15 stoichiometric amounts of potassium carbonate and a mixed solvent (DCM / PhCl volume ratio 1:1) were added, and the mixture was reacted at room temperature for 12 hours to obtain crude camphorene diamine. The aqueous phase of the crude product was extracted with toluene, the organic phases were combined and washed with water, dried, filtered to remove the desiccant, and concentrated. The concentrate was recrystallized from n-heptane to an HPLC purity >95%. The product was air-dried at room temperature to obtain an intermediate with a yield of 90%.

[0090] Synthesis of camphorene tertiary amine compounds

[0091] Under nitrogen protection, 85g of camphorene diamine, 10g of 4-bromobiphenyl, and 80mL of toluene were added to the reaction flask.

[0092] 2.5 g of sodium tert-butoxide was added, stirred, and heated to 70-80 °C. 0.40 g of Pd₂(dba)₃ was slowly added. After the addition was complete, the temperature was further increased to 100-105 °C and refluxed for 2 hours. After the reaction was complete, the mixture was cooled, and the reaction system was extracted with toluene. The organic phase was washed with water, dried, filtered to remove the desiccant, and concentrated. The concentrate was recrystallized from the column in toluene to an HPLC purity >99%, with a product yield of 70%. Example 2

[0093] (1) Synthesis of camphorene diamine

[0094] Under nitrogen protection, 98 g (1 mol) of camphorene, 30% mol of camphorene thiol, and 15% mol of camphorene Mes-Acr-Ph were added to a 250 mL reaction flask. + 15 stoichiometric amounts of potassium carbonate and a mixed solvent (DCM / PhCl volume ratio 1:1) were added, and the mixture was reacted at room temperature for 12 hours to obtain crude camphorene diamine. The aqueous phase of the crude product was extracted with toluene, the organic phases were combined and washed with water, dried, filtered to remove the desiccant, and concentrated. The concentrate was recrystallized from n-heptane to an HPLC purity >95%. The product was air-dried at room temperature to obtain an intermediate with a yield of 90%.

[0095] (2) Synthesis of camphorene tertiary amine compounds

[0096] Under nitrogen protection, 90g of camphorene diamine and 5g of 2-bromophenyl-9-phenylcarbazole were added to the reaction flask.

[0097] 60 mL of toluene and 1.5 g of sodium tert-butoxide were stirred and heated to 70-80 °C. 0.20 g of Pd₂(dba)₃ was slowly added. After the addition was complete, the temperature was raised to 100-105 °C and refluxed for 1.5 h. After the reaction was complete, the mixture was cooled, and the reaction system was extracted with toluene. The organic phase was washed with water, dried, filtered to remove the drying agent, and concentrated. The concentrate was recrystallized from the column with toluene to an HPLC purity >99%, with a product yield of 83%. Example 3

[0098] (1) Synthesis of camphorene diamine

[0099] Under nitrogen protection, 98 g (1 mol) of camphorene, 30% mol of camphorene thiol, and 15% mol of camphorene Mes-Acr-Ph were added to a 250 mL reaction flask. +15 stoichiometric amounts of potassium carbonate and a mixed solvent (DCM / PhCl volume ratio 1:1) were added, and the mixture was reacted at room temperature for 12 hours to obtain crude camphorene diamine. The aqueous phase of the crude product was extracted with toluene, the organic phases were combined and washed with water, dried, filtered to remove the desiccant, and concentrated. The concentrate was recrystallized from n-heptane to an HPLC purity >95%. The product was air-dried at room temperature to obtain an intermediate with a yield of 90%.

[0100] (2) Synthesis of camphorene tertiary amine compounds

[0101] Under nitrogen protection, 85 g of camphorene diamine, 8 g of 2-(4-bromophenyl)naphthalene, 120 mL of toluene, and 3.4 g of sodium tert-butoxide were added to a reaction flask. The mixture was stirred and heated to 70-80 °C. 0.75 g of Pd₂(dba)₃ was slowly added. After the addition was complete, the temperature was raised to 100-105 °C and refluxed for 1 hour. After the reaction was complete, the mixture was cooled, and the reaction system was extracted with toluene. The organic phase was washed with water, dried, filtered to remove the desiccant, and concentrated. The concentrate was recrystallized from the column in toluene to an HPLC purity >99%, with a product yield of 86%.

[0102] The above embodiments are merely further illustrations of the compounds of the present invention, and the scope of protection of the present invention is not limited thereto. For those skilled in the art, various additions and modifications to the present invention without departing from the technical concept described in the claims also fall within the scope of protection of the present invention.

Claims

1. A method for preparing a polyurethane catalyst for rubber rollers using camphorene as a starting material, characterized in that, The catalyst is obtained by carbon-nitrogen coupling reaction using camphorene as raw material to obtain tertiary amine compounds with various structures, and one or more of them are used as catalysts for curing polyurethane for rubber rollers. The structural formula of the camphorene tertiary amine compound prepared from camphorene is shown in Figure 1. ； Among them, R1 and R2 are the same or different substituted aryl or heteroaryl groups; The preparation steps of the polyurethane-cured catalyst for the rubber roller are as follows: （1） ； （2） ； Where X is I, Br, or Cl; Camphorene tertiary amine compounds are synthesized by carbon-nitrogen coupling reaction of camphorene diamine and haloaryl or haloheteroaryl compounds. The camphorene diamine is synthesized as a primary amine via a one-step metal-free catalytic hydrogenation amination of camphorene and ammonium carbonate; ammonium carbonate is used as the ammonia source for the primary amine, with the organic salt Mes-Acr-Ph at E*red = +2.20 V. ＋ As a photocatalyst; R1 and R2 are each independently selected from the group consisting of the following substituents, as shown in 1-12: 。 2. The method for preparing a polyurethane catalyst for rubber rollers using camphorene as a starting material according to claim 1, characterized in that, The tertiary amine compounds are those with structures as shown in 1 to 66: 。

Images