阅读说明：本技术 潜催化剂 (Latent catalysts ) 是由 白晨艳 陈红宇 T·施密特 余英丰 董海军 于 2019-04-18 设计创作，主要内容包括：一种共聚结晶潜催化剂,包括以下的反应产物：(a)至少一种结晶丙烯酸酯单体；(b)至少一种可共聚催化剂化合物；(c)至少一种引发剂；(d)至少一种链转移剂；(e)任选地至少一种溶剂以提供聚合的潜催化剂组合物；以及制备上述潜催化剂的方法。(A co-crystallizing latent catalyst comprising the reaction product of: (a) at least one crystalline acrylate monomer; (b) at least one copolymerizable catalyst compound; (c) at least one initiator; (d) at least one chain transfer agent; (e) optionally at least one solvent to provide a polymerized latent catalyst composition; and a process for preparing the above latent catalyst.)

1. A co-crystallizing latent catalyst comprising the reaction product of:

(a) at least one crystalline acrylate monomer;

(b) at least one copolymerizable catalyst compound;

(c) at least one initiator; and

(d) at least one chain transfer agent.

2. The catalyst of claim 1, further comprising (e) at least one solvent.

3. The catalyst of claim 1, wherein the crystalline acrylate monomer is an acrylate monomer having an alkyl chain of 14 carbons to 22 carbons.

4. The catalyst of claim 1, wherein the crystalline acrylate monomer is selected from the group consisting of: octadecyl acrylate, octadecyl methacrylate, behenyl acrylate, behenyl methacrylate, and mixtures thereof.

5. The catalyst of claim 1, wherein the concentration of the crystalline acrylic monomer is from 42 wt% to 92 wt%.

6. The catalyst of claim 1, wherein the copolymerizable catalyst compound is a tin-containing catalyst compound.

7. The catalyst of claim 6, wherein the tin-containing catalyst compound is dibutyltin maleate.

8. The catalyst of claim 1, wherein the concentration of the copolymerizable catalyst compound is from 1 to 50 weight percent.

9. The catalyst of claim 1, wherein the catalyst has a melting point of 45 ℃ to 60 ℃.

10. The catalyst of claim 1, wherein the catalyst has a crystallization temperature of 40 ℃ to 55 ℃.

11. A process for preparing a co-crystallizing latent catalyst comprising the steps of:

(I) mixing (a) at least one crystalline acrylate monomer; (b) at least one copolymerizable catalyst compound; (c) at least one initiator; (d) at least one chain transfer agent; and

(II) heating the mixture of step (I) at a temperature sufficient to react the components of the mixture and form a co-crystallizing latent catalyst.

12. The method of claim 11, wherein step (I) further comprises (e) at least one solvent.

13. A crystalline latent catalyst composition comprising a mixture of:

(a) at least one crystalline acrylate monomer;

(b) at least one copolymerizable catalyst compound;

(c) at least one initiator; and

(d) at least one chain transfer agent.

14. The catalyst composition of claim 13, further comprising (e) at least one solvent.

15. A method of preparing a crystalline latent catalyst composition comprising mixing:

(a) at least one crystalline acrylate monomer;

(b) at least one copolymerizable catalyst compound;

(c) at least one initiator; and

(d) at least one chain transfer agent.

16. The method of claim 15, further comprising (e) at least one solvent.

Technical Field

The present invention relates to latent catalysts; more particularly, the present invention relates to a co-crystallized polymeric latent catalyst useful in a variety of curable formulations.

Background

Thermosetting resins and other curable compositions or formulations require storage stability at ordinary operating temperatures for the purpose of simplifying handling, and various latent catalysts have been previously developed for this purpose. In general, a latent catalyst means a catalyst having excellent storage stability at a usual operation temperature (e.g., ambient temperature, i.e., 25 ℃). Latent catalysts having excellent storage stability do not exhibit their catalytic activity (do not promote curing or become active) at the usual operating low temperatures until heated to a temperature above the operating temperature. Therefore, the catalyst has catalytic activity when heated at high temperatures. Latent catalysts are used in formulations to improve the storage stability (also referred to as pot life or pot life) of the formulation. However, it is also desirable to provide formulations having excellent curability such that when the latent catalyst is activated to cure, the formulation will cure at a faster cure speed.

Methods for making latent catalysts suitable for use in various formulations to promote reaction of components in the formulation are known. For example, known prior art processes for making latent catalysts include, inter alia, catalyst encapsulation processes; a photo-initiated catalyst method; a closed catalyst method; a catalyst process comprising a tin compound bonded to a ligand; and various methods using reactive components such as tin compounds that react with zinc, organolead, lead salts, amines, or acids.

Generally, however, the above-described known prior art methods of latent catalyst manufacture suffer from one or more problems that prevent these known methods from manufacturing latent catalysts that provide formulations with long pot lives and fast cure speeds. For example, the encapsulated catalyst is substantially separated from the reactive components until sufficient pressure is applied to the catalyst to release the catalyst from the encapsulation. In some thermally activated catalyst processes, the activation temperature is too high (e.g., 80 degrees Celsius [ ° C ] to 140 ℃) to accelerate curing; or the reaction is too complex.

Accordingly, there is a need to provide a latent catalyst that provides formulations having long pot life and fast cure speed without the problems encountered in the prior art.

Disclosure of Invention

The present invention relates to latent catalysts prepared using a copolymerization process, wherein the process comprises grafting a catalyst into a crystalline polymer backbone to form a catalyst grafted crystalline polymer latent catalyst composition. The grafted latent catalyst may then be added to the curable formulation or composition. The graft polymer latent catalyst remains inactive (deactivated) during the first operating temperature of the curable formulation below the melting point of the crystalline polymer. Thereafter, when the curable formulation is subjected to a second curing temperature (i.e., a temperature above the operating temperature) that is above the melting point of the crystalline polymer, the catalyst is activated (i.e., the catalyst is activated by heating when the temperature is raised to curing conditions), and then the reaction between the components in the curable formulation is accelerated to effect curing. During the period in which the latent catalyst remains deactivated at the first operating temperature, advantageously no significant impairment of the pot life of the curable formulation is observed.

In a preferred embodiment, the present invention relates to a co-crystallizing latent catalyst comprising the reaction product of: (a) at least one crystalline monomeric compound, such as a crystalline acrylate monomer, such as crystalline octadecyl acrylate forming a crystalline Polymer (e.g., 18AA available from Scientific Polymer); (b) at least one copolymerizable catalyst, such as a latent catalyst compound containing tin, such as dibutyltin maleate (DBTM), which can be grafted to the crystalline polymer backbone to form a catalyst-grafted crystalline polymer latent catalyst; (c) at least one initiator, such as 2, 2' -Azobisisobutyronitrile (AIBN); and (d) at least one chain transfer agent, such as dodecyl mercaptan (DDM). In another embodiment, the above catalyst may comprise at least one solvent, such as toluene, as component (e).

In another embodiment, the present invention includes a method for making the above-described co-crystallizing latent catalyst. For example, in one preferred embodiment, the process or method of preparing the co-crystallizing latent catalyst involves a co-polymerization process for polymerizing a copolymerizable catalyst, e.g., a tin-containing latent catalyst compound (e.g., DBTM), with a crystalline polymer, e.g., crystalline octadecyl acrylate (e.g., 18AA) to fix the catalyst to the crystalline polymer; and thus form the catalyst structure. In one embodiment, for example, the copolymerization process of the present invention forms a catalyst structure such as that shown in scheme (I) below:

some advantages of the latent catalyst of the present invention include providing: (1) curable formulations containing the latent catalysts of the present invention exhibit excellent pot life; (2) latent catalysts that can be activated at low activation temperatures (e.g., less than 80 ℃) without compromising the pot life of formulations containing such latent catalysts; and (3) curable formulations containing the latent catalysts of the present invention that do not include complex reaction components.

Detailed Description

By "latency" with respect to the catalyst is meant herein that the catalyst does not catalyze a reaction under certain conditions, such as operating temperature, while the catalyst does begin catalyzing the same reaction under other, different conditions (e.g., by increasing the temperature of the reaction).

A "thermally latent catalyst" is a catalyst that is not in its active state at a first, low temperature (e.g., at room temperature of 25 ℃) prior to heating the catalyst to a second, high temperature (e.g., 40 ℃).

By "pot life" with respect to the curable formulation is meant herein the period of time before the viscosity of the curable formulation increases to a point where the curable formulation is no longer suitable for handling in an application.

In one broad embodiment, the latent catalyst composition of the present invention comprises a co-crystallizing latent catalyst, wherein the catalyst is the reaction product of: (a) at least one crystalline polymer, such as a polymer made from a crystalline acrylate monomer; (b) at least one copolymerizable catalyst compound, such as DBTM; (c) at least one initiator, such as AIBN; (d) at least one chain transfer agent, such as DDM; and (e) optionally at least one solvent, such as toluene. By using a copolymerization process, the resulting copolymeric DBTM catalyst provides the desired latency at operating temperatures and begins catalysis at elevated temperatures.

The crystalline acrylate monomer compounds suitable for use in the present invention may be selected from acrylate monomers having long alkyl chains, for example alkyl chains having carbons in the range of 14 carbons to 22 carbons. For example, the crystalline acrylate monomer compound may include one or more of the following compounds: tetradecyl acrylate, tetradecyl methacrylate, hexadecyl acrylate, octadecyl methacrylate, behenyl acrylate, behenyl methacrylate, and mixtures thereof. In a preferred embodiment, the crystalline acrylate monomer compound may be octadecyl acrylate, octadecyl methacrylate, behenyl acrylate, behenyl methacrylate, and mixtures thereof. In another preferred embodiment, the crystalline acrylate monomer compound used in the present invention is octadecyl acrylate.

The amount of crystalline acrylate monomer compound used to prepare the catalyst composition of the present invention may be, for example, 42 weight percent (wt%) to 92 wt% in one embodiment, 47 wt% to 90 wt% in another embodiment, and 52 wt% to 88 wt% in another embodiment.

Copolymerizable catalyst compounds suitable for use in the present invention can include, for example, tin-containing catalyst compounds, as well as any other catalyst having a free radically polymerizable double bond and mixtures thereof. For example, in one preferred embodiment, the present invention may employ a tin-containing catalyst; and the tin-containing catalyst may include any catalyst compound containing a polymerizable C ═ C bond. In another preferred embodiment, the copolymerizable catalyst compound used in the present invention is dibutyltin maleate (DBTM).

The amount of copolymerizable catalyst compound used to prepare the catalyst composition of the present invention can be, for example, from 1 to 50 wt% in one embodiment, from 3 to 45 wt% in another embodiment, and from 5 to 40 wt% in another embodiment.

Initiators are employed in the latent catalyst compositions of the present invention to help initiate polymerization of the acrylate monomers. Conventional initiators may be used and include, for example, azo compound initiators, organic peroxides, organic hydroperoxides, and mixtures thereof. Typical initiators useful in the present invention include, for example, azo initiators such as 2, 2 ' -azobisisobutyronitrile, 2 ' -azobis-2-methylbutyronitrile, 2 ' -azobis (2, 4-dimethylvaleronitrile), 2 ' -azobis (2-methyl-propionitrile), 2 ' -azobis (2-methylbutyronitrile), 1 ' -azo (cyclohexanecarbonitrile), 4 ' -azo-bis (4-cyanovaleric acid), and mixtures thereof. In a preferred embodiment, 2, 2' -azobisisobutyronitrile is used as the initiator in the present invention.

The amount of initiator used to prepare the latent catalyst composition of the invention may be from 0.01 wt% to 5 wt% in one embodiment, based on the total weight of the final composition; in another embodiment, 0.1 wt% to 4 wt%; and in another embodiment, from 0.2 wt% to 3 wt%.

Chain transfer agents are employed in the latent catalyst compositions of the present invention to control the molecular weight of the final polymer. Conventional chain transfer agents may be used and include, for example, mercaptans such as dodecyl mercaptan (DDM) and dodecyl mercaptan (DDA); and halocarbons, such as carbon tetrachloride, and mixtures thereof. In a preferred embodiment, the present invention uses DDM.

The amount of chain transfer agent used in the present invention may be from 0.01 wt% to 10 wt% in one embodiment, from 0.5 wt% to 9 wt% in another embodiment, and from 1 wt% to 8 wt% in another embodiment, based on the total weight of the final composition.

The co-crystallized latent catalyst of the present invention may be formed by polymerization in the presence of a solvent. In one general embodiment, conventional solvents that can dissolve the acrylate monomer and DBTM are used in the latent catalyst composition of the present invention. For example, the solvent may be benzene, toluene, and mixtures thereof. In a preferred embodiment, toluene is used in the present invention.

The amount of solvent suitable for use in the present invention, such as toluene, may be from 60 wt% to 200 wt% in one embodiment, based on the total weight of the final composition; in another embodiment, 80 wt% to 180 wt%; and in another embodiment, 100 wt% to 160 wt%.

In a general embodiment, the method of preparing the co-crystallized latent catalyst composition of the present invention comprises the steps of:

(I) mixing (a) at least one crystalline acrylate monomer compound, such as the crystalline acrylate monomers described above; (b) at least one copolymerizable catalyst compound, such as those described above; (c) at least one initiator, such as AIBN described above; (d) at least one chain transfer agent, such as the above-described DDM; and (e) optionally at least one first solvent, such as toluene, described above;

(II) further mixing the components of step (I) to form a homogeneous mixture;

(III) increasing the temperature of the mixture of step (II) while stirring the mixture up to a temperature of 60 ℃ to 80 ℃ and holding the mixture at this temperature for 24 hours (hr) until a copolymer is formed in the solvent solution;

(IV) precipitating the copolymer from the solvent solution into a second solvent, such as methanol; and

(V) heating the precipitate from step (IV) in a vacuum oven to a temperature of 40 ℃ to strip any residual solvent for 24 hours to form the final co-crystallized latent catalyst after stripping the solvent.

Once the co-crystallizing latent catalyst of the present invention is prepared, the latent catalyst may be added to a curable formulation to provide a curable composition that does not cure at a first low temperature and has excellent storage stability (pot life) at the first low temperature. The first low temperature comprises a temperature below the melting temperature of the latent catalyst for co-crystallization. The co-crystallizing latent catalyst of the present invention may exhibit crystallization behavior, i.e., the catalyst may melt and begin to flow when the catalyst is subjected to a second elevated temperature above the melting point of the catalyst. Also, when the catalyst is subjected to a first low temperature, i.e., a temperature below the melting point of the catalyst, the catalyst may begin to crystallize and become solid again. For example, the melting point of the co-crystallizing latent catalyst is from 45 ℃ to 60 ℃; and has a crystallization temperature of 40 ℃ to 55 ℃.

In addition, a co-crystallizing latent catalyst may be added to the curable formulation to provide a curable composition that exhibits rapid cure or rapid development of adhesive strength. For example, when the curable formulation is heated at an elevated curing temperature, such as 50 ℃ to 60 ℃, the curable formulation exhibits higher bond strength for the same curing time. The melting point and crystallization temperature of the catalyst can be tested by any conventional method. For example, in a preferred embodiment, the melting point and crystallization temperature of the catalyst are determined using Differential Scanning Calorimetry (DSC) methods.

In one broad embodiment, the co-crystallizing latent catalysts of the present invention are useful as catalysts for curable polyurethane compositions or formulations requiring a latent period. As one example of an application where a co-crystallization latent catalyst may be used, and without limitation thereto, a co-crystallization latent catalyst may be added to a polyurethane curable formulation to prepare an adhesive formulation.

Examples of the invention

The following examples are provided to illustrate the invention in further detail, but should not be construed to limit the scope of the claims. All parts and percentages are by weight unless otherwise indicated.

Various terms and nomenclature used in inventive examples (inv.ex.) and comparative examples (comp.ex.) are explained in table I below.

TABLE I raw materials

Synthesis of latent catalyst for copolymerization and crystallization

The copolymerizable crystalline catalyst of the present invention was prepared in toluene solution according to the following method: the crystalline acrylate monomer, DBTM, initiator AIBN, chain extender and toluene were mixed together with slow stirring. Then, the temperature of the resulting mixture is raised to a temperature of 60 ℃ to 80 ℃ with continuous stirring; and the temperature of the mixture was maintained at 60 ℃ to 80 ℃ for 24 hours. After this time, the stirring of the mixture was stopped and cooled. The resulting copolymer was precipitated into methanol and the precipitate was placed in a 40 ℃ vacuum oven for 24 hours to strip off any residual solvent. The final copolymerization catalyst is obtained after the stripping step described above.

Examples 1 to 4

Four samples of latent catalysts according to the invention (inventive examples 1-4) were prepared using the procedure described above for the synthesis of a copolymerisable crystalline catalyst. In each catalyst sample prepared, both the DBTM concentration and the acrylate monomer type were varied; and each of the resulting copolymers exhibits a crystallization temperature and a melting temperature. Details of the above samples are listed in table II.

TABLE II-Co-crystallizing catalyst

The use of latent catalysts prepared as described above is obvious to the person skilled in the art; also for example, in one embodiment, The latent catalyst may be used as an additive in a conventional polyurethane formulation, wherein The polyurethane formulation includes an isocyanate (NCO) prepolymer component, such as MF706A (available from The Dow Chemical Company) and a hydroxyl (OH) component, such as C79 (available from The Dow Chemical Company).