Low odor ultra-clean moisture-cured pur compositions for automotive interiors and methods of making the same

Abstract

The application provides a low-odor super-clean wet-curing PUR composition for automotive interiors and a preparation method thereof, which is prepared from the following raw materials in mass percentage: 10-20% of acrylic resin; 42-65% of polyhydric alcohol; 0.1-1% of an organic skeleton containing a reactive group; 20-30% of isocyanate; 1-5% of a chain extender; and 0-3% of a catalyst. The organic skeleton containing the reactive group is bonded to the polyurethane chain through the isocyanate to become part of the PUR, effectively locking the small-molecule volatile substances into the porous skeleton, preventing the high-temperature volatilization of the small-molecule compounds, solving the high-temperature odor problem of the PUR glue, and being more environmentally friendly than the traditional PUR glue.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering and relates to an adhesive, specifically a low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors and its preparation method. Background Technology

[0002] Moisture-curing polyurethane (PUR) hot melt adhesives are a type of polyurethane hot melt adhesive containing terminal isocyanate groups. They develop high initial strength through physical cooling and then fully cure through reaction with moisture from the environment or substrate surface, forming a thermosetting polymer with high cohesive strength. Due to their solvent-free, environmentally friendly, and low-temperature operating characteristics, they meet the requirements for adhesives used in automotive interiors. In contrast, flame-cured composite sponges undergo violent decomposition during combustion, producing burnt, aromatic hydrocarbon, bitter almond, fishy, ​​and rancid odors, severely impacting in-vehicle comfort and the health of drivers. Therefore, moisture-curing polyurethane hot melt adhesives are increasingly favored in automotive interior materials.

[0003] When ordinary PUR hot melt adhesive cures, it also contains unreacted residual MDI monomers, which easily volatilize at high temperatures. MDI has a strong, pungent odor, which is a major reason why PUR adhesives have a mild odor at room temperature but a foul and irritating odor at high temperatures. When used as automotive interior materials, this pungent odor not only poses safety concerns but also negatively impacts people's mood and feelings. Furthermore, because isocyanate-terminated polyurethane prepolymers typically have a molecular weight of only a few thousand Daltons, their initial bond strength is relatively poor. To obtain better initial bond strength, polymers with high crystallinity, such as acrylic resins, are often added to the prepolymer system. Acrylic resins have good compatibility with polyurethane systems and are therefore widely used. However, this also increases the application temperature and causes problems such as increased fiber size. Summary of the Invention

[0004] To address the aforementioned technical problems in the prior art, this invention provides a low-odor, ultra-clean moisture-curing PUR composition for automotive interiors and its preparation method. This low-odor, ultra-clean moisture-curing PUR composition for automotive interiors and its preparation method aim to solve the technical problems of existing moisture-curing PUR adhesives, such as high-temperature odor irritation, low initial adhesion, and poor peel strength, as well as technical problems such as high processing viscosity, generation of a large amount of fly filaments, and impact on production efficiency.

[0005] This invention provides a low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors, prepared from the following raw materials in the indicated weight percentages:

[0006] Acrylic resin: 10%-20%,

[0007] Polyols: 42%-65%,

[0008] Organic skeletons containing reactive groups: 0.1-1%,

[0009] Isocyanate: 20%-30%,

[0010] Chain extender: 1%-5%,

[0011] Catalyst: 0-3%;

[0012] The organic framework containing reactive groups is a COF covalent organic framework material.

[0013] Furthermore, the organic framework containing reactive groups is a COF-LZU1 (benzene-1,3,5-tricarboxaldehyde and benzene-1,4-diamine) covalent organic framework material, a COF-v (1,3,5-tris(4-aminophenyl)benzene and 1,4-dialdehyde-2,5-divinylbenzene) covalent organic framework material, a COF-366 (5,10,15,20-tetra(4-benzaldehyde)porphyrin and p-phenylenediamine) covalent organic framework material, or a COF-Tz covalent organic framework.

[0014] Furthermore, the acrylic resin is a non-reactive acrylic resin that does not contain active hydrogen.

[0015] Furthermore, the polyol is any one or a combination of two of polyester polyols or polyether polyols.

[0016] Furthermore, the isocyanate is a monomer, dimer, or trimer of an aromatic isocyanate.

[0017] Furthermore, the chain extender is any one or a combination of two or more of low molecular weight polyols, polyamines, or compounds containing active hydrogen.

[0018] Furthermore, the catalyst is a mixture of a polyhydroxy tertiary amine catalyst and a tin-based catalyst.

[0019] The present invention also provides a method for preparing the above-mentioned low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors, characterized by comprising the following steps:

[0020] S1, weigh out the following components by mass percentage: acrylic resin, polyol, organic framework containing reactive groups, isocyanate, chain extender, and catalyst.

[0021] S2, add acrylic resin, polyol and chain extender to the reactor, heat to 155-165℃ and keep the temperature constant, stir and melt evenly;

[0022] S3, steam is introduced into the reactor to strip the raw materials for 3-6 hours. After the treatment is completed, nitrogen is introduced into the reactor and then vacuumed for 2-3 hours.

[0023] S4, cool down to 75-85℃, add isocyanate and an organic framework containing reactive groups pre-activated by vacuum at 100-120℃ into the reactor, keep the temperature constant and react for 0.5-2 hours, raise the temperature to 105-115℃, evacuate the vacuum, then add the catalyst and continue evacuating the vacuum.

[0024] S5, during material feeding, the finished product is filtered to obtain a low-odor, ultra-clean, moisture-cured PUR composition for automotive interiors.

[0025] In this invention, by introducing an organic framework containing reactive groups and bonding it with isocyanate into the polyurethane chain to become part of the PUR composition, small molecule volatile substances are effectively locked into the porous framework to prevent VOC volatilization.

[0026] Furthermore, the organic framework containing reactive groups includes, but is not limited to, COF-LZU1 (benzene-1,3,5-tricarboxaldehyde and benzene-1,4-diamine) covalent organic framework material, COF-v (1,3,5-tris(4-aminophenyl)benzene and 1,4-dialdehyde-2,5-divinylbenzene) covalent organic framework material, COF-366 (5,10,15,20-tetra(4-benzaldehyde)porphyrin and p-phenylenediamine) covalent organic framework material, COF-Tz covalent organic framework, etc., which can be transformed into a porous framework structure as shown below after vacuum heat treatment:

[0027] The COF covalent organic framework material, due to its porous structure, can absorb the small molecule volatiles remaining in this invention, which is beneficial to odor control.

[0028] Furthermore, the acrylic resin is a non-reactive acrylic resin that does not contain active hydrogen.

[0029] Furthermore, the acrylic resin includes, but is not limited to, methyl methacrylate, butyl methacrylate, docosyl methacrylate, isooctyl acrylate, N,N-dimethylacrylamide, isobornyl acrylate, isodecanyl acrylate, cyclohexyl methacrylate, etc. The acrylic resin has good crystallinity and low melt viscosity, good compatibility with PUR systems, and low viscosity, which can improve initial tack.

[0030] Furthermore, the polyol comprises one or more mixtures of polyester polyol and polyether polyol.

[0031] Furthermore, the polypolyols include, but are not limited to, one or more mixtures of poly(1,6-hexanediol adipate) (PHA), poly(1,4-butanediol adipate) (PBA), polyethylene adipate (PEA), polycaprolactone (PCL), polytetrahydrofuran diol (PT-MEG), polytetrahydrofuran ether diol (PTMG), polypropylene oxide diol (PPG), and tetrahydrofuran-propylene oxide copolydiol.

[0032] More preferably, the polyol is a mixture of polyester polyol and polyether polyol in a mass ratio of (60-80):(20-40).

[0033] Furthermore, the isocyanate is a monomer, dimer, or trimer of an aromatic isocyanate, including but not limited to toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophthalimide diisocyanate (XDI), hydrogenated phthalimide diisocyanate (HXDI), etc.

[0034] Furthermore, the chain extender is any one of low molecular weight polyols, polyamines, or compounds containing active hydrogen.

[0035] Furthermore, the chain extender is selected from 1,4-butanediol (BDO).

[0036] Furthermore, the catalyst is a mixture of a polyhydroxy tertiary amine catalyst and a tin-based catalyst. The polyhydroxy tertiary amine catalyst not only possesses catalytic activity but is also a component of the polyurethane molecular chain, which is beneficial for reducing odor.

[0037] Furthermore, the polyhydroxy compound is selected from reactive tertiary amine catalysts containing -OH, such as N,N,N′-trimethyl-N′-hydroxyethyl-diaminoethyl ether, N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, and 2-(2-dimethylaminoethoxy)ethanol.

[0038] The organotin catalysts include, but are not limited to, dibutyltin dilaurate, stannous octoate, stannous oleate, mercaptotin, and 2-(di-n-butyl)diketonetin.

[0039] Furthermore, the catalyst is selected from polyhydroxy compounds and organotin catalysts at a ratio of 1:1 to 1:10.

[0040] Compared with existing technologies, the technical effects of this invention are positive and obvious:

[0041] (1) The organic framework containing reactive groups used in this invention has a porous structure, which can absorb residual isocyanates, acrylic acid and other small molecule monomers, small molecule VOCs and so on, which is beneficial to odor. On the other hand, the organic framework containing reactive groups can bond with isocyanates and enter the polyurethane chain to become part of the PUR composition. It has a stable structure and good compatibility with PUR organics.

[0042] (2) A reactive tertiary amine catalyst containing -OH is used in combination with a tin catalyst. The reactive tertiary amine catalyst containing -OH reacts with -NCO in the prepolymer and enters the polyurethane chain segment. During use, the catalyst volatilization can be avoided, and the odor of the glue is more friendly.

[0043] (3) The preparation process of the present invention, such as using steam or nitrogen to treat the raw materials, can remove small volatile molecules in the raw materials, which is beneficial to reducing odor. Detailed Implementation

[0044] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments are used to specifically illustrate the low-odor ultra-pure moisture-curing PUR composition for automotive interiors and its preparation method.

[0045] Example 1

[0046] In this embodiment, the low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors includes acrylic resin, polyol, organic framework containing reactive groups, isocyanate, chain extender, and catalyst.

[0047] The mass percentage of the above substances is:

[0048] Acrylic resin: Polypolyol: Organic backbone containing reactive groups: Isocyanate: Chain extender: Catalyst = 15%: 55%: 0.8%: 25%: 3%: 1.2%.

[0049] In this embodiment, the acrylic resin is selected from docosyl methacrylate (THFA, Dixin Chemical), the isocyanate is selected from diphenylmethane diisocyanate (MDI, Wanhua Chemical), and the polypolyol is a mixture of polytetrahydrofuran ether diol (PTGM2000, Dow Chemical) and polycaprolactone polyol (PCL 2000, PEG Works, USA), wherein the mass ratio of polytetrahydrofuran ether diol to polycaprolactone polyol is 6:4 (unless otherwise specified, all ratios are based on mass). The chain extender is selected from 1,4-butanediol (BDO), the reactive organic skeleton is selected from COF-v covalent organic skeleton (Qiyue Biotechnology), and the catalyst is selected from a mixture of dibutyltin dilaurate and N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, wherein the mass ratio of dibutyltin dilaurate to N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine is 1.3:1.

[0050] The method for preparing the above-mentioned low-odor, ultra-clean, moisture-cured PUR composition for automotive interiors includes the following steps:

[0051] During the preparation process, all components were added according to the aforementioned mass ratios. The specific preparation process is as follows:

[0052] Step S1: Add polypropylene glycol, polyester polyol, 1,4-butanediol and docosyl methacrylate to the reactor, heat to 160°C and keep the temperature constant, stir and melt evenly, wherein the stirring rate is 1000±50 r / min.

[0053] Step S2: Steam is introduced into the reactor to strip the raw materials. Stirring is continued for 3-6 hours. After the treatment is completed, nitrogen is introduced into the reactor and then vacuumed for 2-3 hours. The stirring rate is 500±50 r / min.

[0054] Step S3: Cool down to 80°C, add MDI and pre-vacuum-treated COF-v covalent organic framework to the reactor, maintain constant temperature for 1 hour, raise temperature to 110°C, evacuate for 1 hour, then add dibutyltin dilaurate and N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, continue evacuation for 30 minutes, with stirring rate of 1200±50 r / min, vacuum pretreatment temperature of 120°C, and pretreatment time of 4-8 hours;

[0055] Step S4: When discharging the material, allow the finished product to pass through a filter to obtain a low-odor, ultra-pure PUR composition.

[0056] The reactive covalent organic framework used in this invention undergoes vacuum pretreatment followed by self-assembly to obtain a regularly arranged organic framework channel. This channel can adsorb and incorporate small molecule volatiles into the framework, and the absorbed or purified organic matter will not be released at high temperatures, which is beneficial for purifying high-temperature odors. At the same time, its reactive groups, such as NH2-, can chemically bond with isocyanate groups, integrating the organic framework into the PUR main bond. It also exhibits good compatibility with PUR, becoming part of the PUR. The regularly arranged organic framework has crystallinity, which can also improve the crystallinity of PUR, further shortening the curing time and accelerating the material turnover and delivery speed of automotive interior composite materials.

[0057] Example 2

[0058] Compared to Example 1, the raw materials differ in Example 2 as follows: the acrylic resin used isobornyl acrylate (IOBA, Dixin Chemical), and the mass ratio of polytetrahydrofuran ether diol to polycaprolactone polyol is 7:4. The preparation method of the moisture-curing PUR is the same as in Example 1 and is omitted here.

[0059] Example 3

[0060] Compared to Example 1, the different raw materials in Example 3 are: 18 wt% docosyl methacrylate, 22 t% MDI, and 55 t% polypolyol, wherein the mass ratio of polytetrahydrofuran ether diol to polycaprolactone polyol is 7:4. The preparation method of the moisture-curing PUR is the same as in Example 1 and is omitted here.

[0061] Example 4

[0062] Compared to Example 1, the raw materials in Example 4 are different: the polyols selected are a mixture of polytetrahydrofuran ether glycol (PTGM2000, Dow Chemical), polypropylene glycol (PPG 400, Dow Chemical), and polycaprolactone polyol (PCL 2000, PEG Works, USA), wherein the mass ratio of polyether polyol to polyester polyol is 6:4, and the mass ratio of PTGM 2000 to PPG400 is 12:10. The content of COF-v covalent organic framework (Qiyue Biotechnology) is increased to 1 wt%, and the content of docosanoyl methacrylate is reduced to 14.7 wt%. The preparation method of the moisture-cured PUR is the same as in Example 1 and is omitted here.

[0063] Example 5

[0064] Compared to Example 1, the raw materials in Example 5 are different as follows: the acrylic resin is selected from isoborneol acrylate (IOBA, Dixin Chemical) with a content of 15.2 wt%, the isocyanate is selected from toluene diisocyanate (TDI, Wanhua Chemical), and the COF-v covalent organic framework material content is 1 wt%. The preparation method of the hydrothermal curing PUR is the same as that in Example 1, and is omitted here.

[0065] Example 6

[0066] Compared to Example 4, the difference in Example 6 is that: toluene diisocyanate (TDI, Wanhua Chemical) is used as the isocyanate, the content of docosyl methacrylate is 15wt%, and the content of COF-v covalent organic framework material is 0.7wt%. The preparation method of the thermosetting PUR is the same as in Example 1, and is omitted here.

[0067] Comparative Example 1

[0068] Compared to Example 1, Comparative Example 1 did not use acrylic resin, but the other raw materials remained the same. The isocyanate content was 30 wt%, the polyol content was 65 wt%, and the polyol was a mixture of polytetrahydrofuran ether diol and polycaprolactone polyol. The mixing ratio remained the same. The preparation method of the moisture-cured PUR differed from that in Example 1 in that acrylic resin was not added in S1.

[0069] Comparative Example 2

[0070] Compared to Example 6, the different raw materials in Comparative Example 2 are: no reactive organic framework was selected, conventional fragrance and flavor content remained unchanged, and an amine catalyst without active hydrogen (DMDEE) was selected. The preparation method of the hydrothermal curing PUR differs from that in Example 1 in that the fragrance and flavor without reactive organic framework is added in S3.

[0071] Comparative Example 3

[0072] Compared to Comparative Example 2, Comparative Example 3 differs in that the amine catalyst used is a non-active hydrogen amine catalyst (DMDEE), while other raw materials remain unchanged. In the method for preparing PUR through hygrothermal curing, step S2, which involves passing steam into the reactor to strip the raw materials, is omitted; all other operations remain the same.

[0073] The dosage (mass ratio) of each component is shown in Table 1.

[0074] Table 1

[0075]

[0076] The PUR samples prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to performance tests, and the test results are shown in Tables 2-4. The performance test methods are as follows:

[0077] Viscosity: Tested at 100°C using RVCT / 28#.

[0078] -NCO content: determined according to ASTM D2572-1997 standard.

[0079] Opening time: Apply approximately 0.1mm thick PURHMA adhesive to white paper, place it in a constant temperature and humidity chamber at 23℃ and 50%RH, and record the time it takes for the paper to become non-sticky to the touch. This is the opening time.

[0080] Odor: The odor level is evaluated subjectively according to the VDA270 standard.

[0081] Formaldehyde emission: Tested according to PV3925-2005 standard.

[0082] Total carbon emissions (μgC / g): tested according to PV 3441:1995 standard.

[0083] Atomization: Tested according to DIN 75201 Method B.

[0084] Initial tack: The prepared PUR composition was dropped onto a PMMA plate, and the shear force between the two plates was tested using a tensile testing machine within 5 minutes.

[0085] Peel strength after lamination: tested according to DIN53357 standard.

[0086] Curing time: The time from when the product is placed in the curing chamber after compounding until it is taken out and tested.

[0087] Table 2

[0088]

[0089]

[0090] Table 3

[0091] Formaldehyde emission (mg / kg) ≤7 1 0 12 16 Nebulized (mg) ≤1 ND ND ND 5 Total carbon volatilization (μgC / g) ≤50 18 8 624 504

[0092] Table 4

[0093]

[0094] As can be seen from Tables 2, 3, and 4, compared with Comparative Example 1, Examples 1-3 show a significant improvement in the initial adhesion of other PUR compositions containing acrylic resin. With the increase of acrylic resin content, the initial adhesion increases, the viscosity rises, the amount of fly filaments increases significantly during lamination, and the peel strength after lamination is improved, all of which can achieve the goal of breaking the sponge material and preventing the delamination of PVC leather and sponge. At the same time, it can accelerate the crystallization speed of the PUR composition and shorten the curing cycle.

[0095] Compared to Comparative Example 2, the odor level, atomization, formaldehyde volatilization, and other organic matter content of the PUR compositions in Examples 1-6, all of which incorporated COF-v covalent organic framework material, were improved. Unlike fragrances and flavorings, which can only mask odors but not alter the volatilization of small molecule volatiles in chemical substances, reactive covalent organic frameworks, after vacuum pretreatment, self-assemble into regularly arranged organic framework channels. These channels can adsorb and incorporate small molecule volatiles into the framework. Furthermore, the absorbed or purified organic matter is not released at high temperatures, indicating that covalent organic framework material is beneficial for purifying high-temperature odors. Simultaneously, its reactive groups, such as NH2-, can chemically bond with isocyanate groups, integrating the organic framework into the PUR main bond. It also exhibits good compatibility with PUR, becoming part of the PUR, and can improve the crystallinity of PUR, shortening the curing time.

[0096] Meanwhile, compared with Comparative Example 2, it can be seen that in Comparative Example 3, no steam stripping treatment was performed on the raw materials during the preparation of the PUR composition. The odor level, atomization, and VOC value of the obtained PUR composition were significantly higher. Therefore, adding steam stripping operation in the raw material processing stage is beneficial to improving the odor.

[0097] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors, characterized in that... It is prepared from the following raw materials by weight percentage: Acrylic resin: 10%-20%, Polyols: 42%-65%, Organic skeletons containing reactive groups: 0.1-1%, Isocyanate: 20%-30%, Chain extender: 1%-5%, Catalyst: 0-3%; The organic framework containing reactive groups is a COF covalent organic framework material; The organic framework containing reactive groups is a COF-LZU1 covalent organic framework material, a COF-v covalent organic framework material, a COF-366 covalent organic framework material, or a COF-Tz covalent organic framework.

2. The low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors according to claim 1, characterized in that: The acrylic resin is a non-reactive acrylic resin that does not contain active hydrogen.

3. The low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors according to claim 1, characterized in that: The polyol is any one or a combination of two of polyester polyols or polyether polyols.

4. The low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors according to claim 1, characterized in that: The isocyanate is a monomer, dimer, or trimer of an aromatic isocyanate.

5. The low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors according to claim 1, characterized in that: The chain extender is a compound containing active hydrogen.

6. The low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors according to claim 1, characterized in that: The chain extender is any one or a combination of two of low molecular weight polyols or polyamines.

7. The low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors according to claim 1, characterized in that: The catalyst is a mixture of a polyhydroxy tertiary amine catalyst and a tin-based catalyst.

8. The method for preparing a low-odor, ultra-clean, moisture-curing PUR composition for automotive interiors as described in claim 1, characterized in that... The steps include the following: S1, weigh out the following components by mass percentage: acrylic resin, polyol, organic framework containing reactive groups, isocyanate, chain extender, and catalyst. S2, add acrylic resin, polyol and chain extender to the reactor, heat to 155-165℃ and keep the temperature constant, stir and melt evenly; S3, steam is introduced into the reactor to strip the raw materials for 3-6 hours. After the treatment is completed, nitrogen is introduced into the reactor and then vacuumed for 2-3 hours. S4, cool down to 75-85℃, add isocyanate and an organic framework containing reactive groups pre-activated by vacuum at 100-120℃ into the reactor, keep the temperature constant and react for 0.5-2 hours, raise the temperature to 105-115℃, evacuate the vacuum, then add the catalyst and continue evacuating the vacuum. S5, during material feeding, the finished product is filtered to obtain a low-odor, ultra-clean, moisture-cured PUR composition for automotive interiors.

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