A hydroxy compound for preparing a two-component solvent-free polyurethane resin and its application

Abstract

The invention provides a hydroxyl composition for preparing a two-component solvent-free polyurethane resin and application thereof. The hydroxyl composition comprises a combination of vegetable oil polyol A, bio-based polyester polyol A and a chain extender. When the hydroxyl composition is used to prepare the polyurethane resin, it is less affected by an external filler, and the amount of the filler added can be increased to 100%. When the hydroxyl composition is used as a raw material for preparing a synthetic leather adhesive layer, it has excellent bonding performance with a water-based surface layer, and the prepared polyurethane resin can also be made biodegradable.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane, and in particular relates to a hydroxy compound for preparing a two-component solvent-free polyurethane resin and application thereof. Background Art

[0002] TPU is a block copolymer composed of isocyanate and polymerized polyols with small molecule polyols as chain extenders as main components. Products with different properties can be obtained by matching different types of curing agents, polyols and chain extenders, which makes TPU products very versatile. TPU also has excellent mechanical properties such as high strength, high elasticity, high wear resistance, high flexibility, and is resistant to oil, solvents and general chemicals. It has been widely used in synthetic leather.

[0003] With the transformation and upgrading of the synthetic leather industry, the market's requirements for environmental protection are getting higher and higher. Downstream synthetic leather customers have increasingly strict requirements for the residual amount of organic solvents in products, and even require zero content of environmental protection. Therefore, solvent-free polyurethane synthetic leather has received widespread attention. CN106397728A discloses a two-component fully dry-paste adhesive layer polyurethane resin for environmentally friendly low-VOC synthetic leather and a preparation method thereof. The polyurethane resin is mainly prepared by the following components in mass parts ratio: 10 to 20 parts of isocyanate; 25 to 40 parts of polyol compounds; 1 to 5 parts of diol chain extenders; 0 to 0.5 parts of antioxidants; organic tin or organic bismuth catalysts, the addition amount is 0.001 to 0.05% of the weight of the polyol compound. The polyurethane resin prepared by the invention greatly improves the bonding performance of the adhesive layer polyurethane resin. Under the conditions of drying the polyurethane film and cleanly evaporating the solvent, the bonding fastness is good, the organic solvent content in the manufactured synthetic leather product is greatly reduced, the environmental protection performance of the product is improved, and it has high market competitiveness.

[0004] However, after adding waste plant residues such as bagasse, which is waste from the sugar industry, as fillers to the A and B materials of conventional solvent-free polyurethane resins, the viscosity of A and B materials increases significantly, making it difficult to add large quantities. At the same time, they are easy to absorb moisture, and some polar substances in them will greatly affect the reaction.

[0005] In addition, with the further advancement of environmental protection policies, zero-solvent synthetic leather will also become an inevitable trend in the future. The mechanical properties of synthetic leather prepared by existing pure water-based technology are poor, and poor hydrolysis resistance seriously restricts its application; and the solvent-free two-component with water-based surface layer, due to the strong hydrophilicity of the water-based surface layer, seriously affects the reaction and makes the production unstable.

[0006] Therefore, developing a hydroxy compound that is less affected by fillers, can be combined with a water-based surface layer, and has excellent hygroscopicity and degradability is a technical problem that urgently needs to be solved in the field. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a hydroxyl compound for preparing a two-component solvent-free polyurethane resin and its application. When the hydroxyl compound is used to prepare the polyurethane resin, it is less affected by the addition of fillers during the preparation process, and the polar substances in the bio-based fillers are not easily dissolved in the hydroxyl compound, so the addition amount of the filler can be increased to 100%. When used as a raw material for preparing a synthetic leather adhesive layer, it has strong hydrophobicity, which can effectively prevent the dissolution of polar substances in the aqueous surface layer from affecting the two-component reaction, thereby achieving excellent bonding performance with the surface layer.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a hydroxy compound for preparing a two-component solvent-free polyurethane resin.

[0010] The hydroxy compound comprises the following components in parts by weight:

[0011] Vegetable oil polyol A 70-90 parts by weight

[0012] Bio-based polyester polyol A 10-30 parts by weight

[0013] Chain extender 1 to 20 parts by weight.

[0014] Among them, the vegetable oil polyol A can be 72 parts by weight, 74 parts by weight, 76 parts by weight, 78 parts by weight, 80 parts by weight, 82 parts by weight, 84 parts by weight, 86 parts by weight or 88 parts by weight.

[0015] The bio-based polyester polyol A can be 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 24 parts by weight, 26 parts by weight, 28 parts by weight, etc.

[0016] The chain extender can be 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight or 18 parts by weight, etc.

[0017] The hydroxy compound for preparing a two-component solvent-free polyurethane resin provided by the present invention comprises a specific portion of a vegetable oil polyol A and a specific portion of a bio-based polyester polyol A; wherein the amount of the vegetable oil polyol A is significantly higher than the amount of the bio-based polyester polyol A, and the crosslinking degree of the two-component solvent-free polyurethane resin prepared by using the hydroxy composition can be improved to a certain extent, but too high a crosslinking degree will also affect the performance of the product, so the above-mentioned specific vegetable oil polyol A and bio-based polyester polyol A are used in a specific amount range; at the same time, when the hydroxy composition is subsequently used to prepare the polyurethane resin, it has good tolerance for the added filler, that is, when a large amount of filler (including waste plant residues, etc.) is added during the preparation of the polyurethane resin, it will not affect the original performance of the polyurethane resin, will not increase the viscosity of the material and is not easy to absorb moisture, so that the filler can be added in large quantities, and the maximum addition amount can be increased to 100%; in addition, the crosslinking degree provided by the vegetable oil polyol added in the hydroxy composition can ensure that the hydroxy compound still has sufficient reaction activity under a large amount of filler, and at the same time, the addition of the bio-based polyester polyol makes the hydroxy compound still have sufficient strength under a large amount of filler, thereby helping to improve the overall performance of the polyurethane product finally obtained.

[0018] The components in the hydroxyl compound provided by the present invention are all biodegradable, so that the polyurethane resin prepared by using the hydroxyl compound also has good biodegradability, and the synthetic leather prepared further has good environmental protection characteristics.

[0019] Preferably, the vegetable oil polyol A includes any one of castor oil polyol, soybean oil polyol or palm oil polyol, or a combination of at least two thereof.

[0020] Preferably, the functionality of the vegetable oil polyol A is not less than 2, for example, 3, 4, 5, 6, 7 or 8, etc.

[0021] Preferably, the functionality of the bio-based polyester polyol A is 2-3.

[0022] Preferably, the hydroxyl value of the bio-based polyester polyol A is 28 to 112 mkgKOH / g, for example, 30 mkgKOH / g, 40 mkgKOH / g, 50 mkgKOH / g, 60 mkgKOH / g, 70 mkgKOH / g, 80 mkgKOH / g, 90 mkgKOH / g, 100 mkgKOH / g or 110 mkgKOH / g, etc.

[0023] Preferably, the raw materials for preparing the bio-based polyester polyol A include bio-based diols and bio-based dibasic acids.

[0024] Preferably, the bio-based diol includes bio-based 1,3-propylene glycol and / or bio-based 1,4-butylene glycol, and more preferably bio-based 1,3-propylene glycol.

[0025] Preferably, the bio-based dibasic acid includes any one of bio-based dimer acid, bio-based succinic acid or bio-based sebacic acid, or a combination of at least two thereof, and more preferably a combination of bio-based succinic acid and bio-based sebacic acid.

[0026] Preferably, the chain extender includes C2-C12 (eg, C4, C6, C8, C10 or C12, etc.) small molecule diols.

[0027] Preferably, the C2-C12 small molecule diol includes any one of ethylene glycol, propylene glycol, butanediol or hexanediol, or a combination of at least two thereof.

[0028] In a second aspect, the present invention provides a method for preparing the hydroxy compound as described in the first aspect, the preparation method comprising: mixing vegetable oil polyol A, bio-based polyester polyol A and a chain extender to obtain the hydroxy compound.

[0029] In a third aspect, the present invention provides a two-component solvent-free polyurethane resin, wherein the raw materials for preparing the two-component solvent-free polyurethane resin include material A, material B and filler;

[0030] The material A comprises the hydroxy compound as described in the first aspect;

[0031] The B material includes a bio-based polyurethane prepolymer.

[0032] Preferably, the raw materials for preparing the bio-based polyurethane prepolymer include diisocyanate and bio-based polyol.

[0033] Preferably, the mass percentage of NCO in the bio-based polyurethane prepolymer is 15-25%, for example, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23% or 24%, etc.

[0034] Preferably, the bio-based polyol comprises vegetable oil polyol B and / or bio-based polyester polyol B.

[0035] Preferably, the mass ratio of the A material to the B material is 100:(50-150), for example, 100:60, 100:70, 100:80, 100:90, 100:100, 100:110, 100:120, 100:130 or 100:140, etc.

[0036] Preferably, the raw materials for preparing the two-component solvent-free polyurethane resin further include any one of a catalyst, a foaming agent or silicone oil, or a combination of at least two of them.

[0037] Preferably, the catalyst comprises a bismuth-zinc composite catalyst.

[0038] Preferably, the filler comprises plant residues.

[0039] In a fourth aspect, the present invention provides a synthetic leather, wherein the synthetic leather comprises the two-component solvent-free polyurethane resin as described in the third aspect.

[0040] Preferably, the two-component solvent-free polyurethane resin is used as the adhesive layer of the synthetic leather.

[0041] In a fifth aspect, the present invention provides a method for preparing the synthetic leather as described in the fourth aspect, the preparation method comprising: mixing material A and an optional catalyst in the two-component solvent-free polyurethane resin as described in the third aspect, adding a filler to mix, then adding material B to mix, and then evenly coating the surface layer for foaming reaction, bonding to a base fabric, and curing to obtain the synthetic leather.

[0042] Preferably, the temperature of the foaming reaction is 80-130°C, such as 90°C, 100°C, 110°C or 120°C.

[0043] Preferably, the foaming reaction time is 2 to 10 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes or 9 minutes.

[0044] Preferably, the curing temperature is 100-160°C, for example, 110°C, 120°C, 130°C, 140°C or 150°C.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The hydroxyl compound for preparing a two-component solvent-free polyurethane resin provided by the present invention comprises a combination of a vegetable oil polyol A, a bio-based polyester polyol A and a chain extender; when the hydroxyl compound is used to prepare the polyurethane resin, it is less affected by the filler added during the preparation process, so that it has a suitable viscosity (1200-2702CPS / 25°C), and the polar substances in the bio-based filler are not easily dissolved in the hydroxyl compound, so that the amount of filler added can be increased to 100%, and when used as a raw material for preparing a synthetic leather adhesive layer, it has strong hydrophobicity, which can effectively prevent the dissolution of polar substances in the aqueous surface layer from affecting the two-component reaction, thereby achieving excellent bonding performance with the surface layer (peel strength is as high as 51-84N / 2.5cm).

[0047] (2) At the same time, since each component in the above-mentioned hydroxyl composition is a degradable material, the prepared polyurethane resin also has good biodegradability (biodegradability is 90-98%), thereby making the synthetic leather further prepared environmentally friendly. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] The detailed information of the raw materials involved in the specific implementation of the present invention is as follows:

[0050] Castor oil polyol: refined first-grade castor oil from Guangzhou Chenshi Chemical Co., Ltd.;

[0051] Palm oil polyol: Maskimi, Malaysia, PKF 3000 brand product;

[0052] Bio-based polyester polyol A1: molecular weight 2000, obtained by reacting bio-based succinic acid and bio-based sebacic acid with 1,3-propylene glycol in a mass ratio of 1.17:1;

[0053] Bio-based polyester polyol A2: molecular weight 2000, obtained by reacting bio-based succinic acid and 1,3-propylene glycol;

[0054] Diisocyanate: Wanhua Chemical MDI;

[0055] Carbodiimide-uretonimine modified MDI: Wanhua MDI-100HL.

[0056] Example 1

[0057] A two-component solvent-free polyurethane resin, wherein the raw materials for its preparation include 100 parts by weight of material A, 100 parts by weight of material B, 0.25 parts by weight of a catalyst and 100 parts by weight of a filler;

[0058] Wherein, the material A comprises the following components in parts by weight:

[0059] 80 parts by weight of castor oil polyol

[0060] Bio-based polyester polyol A1 20 parts by weight

[0061] 1,3-propylene glycol 10 parts by weight;

[0062] The material B is a bio-based polyurethane prepolymer, wherein the mass percentage of NCO groups is 20%.

[0063] The preparation method of the bio-based polyurethane prepolymer comprises: reacting 35 parts by weight of bio-based polyester polyol A1, 55 parts by weight of MDI and 10 parts by weight of carbodiimide-uretonimine modified MDI at 70° C. under nitrogen protection for 3.5 hours to obtain the bio-based polyurethane prepolymer;

[0064] The catalyst includes 0.05 parts by weight of bismuth neodecanoate and 0.2 parts by weight of zinc neodecanoate;

[0065] The filler is bio-based wood powder.

[0066] Example 2

[0067] A two-component solvent-free polyurethane resin, the raw materials for its preparation include, by weight: 100 parts by weight of material A, 100 parts by weight of material B, 0.25 parts by weight of catalyst and 100 parts by weight of filler;

[0068] Wherein, material A comprises the following components in parts by weight:

[0069] Palm oil polyol 70 parts by weight

[0070] Bio-based polyester polyol A1 30 parts by weight

[0071] 1 part by weight of 1,3-propylene glycol;

[0072] The material B is a bio-based polyurethane prepolymer, wherein the mass percentage of NCO groups is 20%.

[0073] The preparation method of the bio-based polyurethane prepolymer comprises: reacting 5 parts by weight of castor oil polyol, 30.5 parts by weight of bio-based polyester polyol A1, 54.5 parts by weight of MDI and 10 parts by weight of carbodiimide-uretonimine modified MDI at 70° C. under nitrogen protection for 3.5 hours to obtain the bio-based polyurethane prepolymer;

[0074] The catalyst includes 0.05 parts by weight of bismuth neodecanoate and 0.2 parts by weight of zinc neodecanoate;

[0075] The filler is bio-based wood powder.

[0076] Example 3

[0077] A two-component solvent-free polyurethane resin, the raw materials for its preparation include, by weight: 100 parts by weight of material A, 100 parts by weight of material B, 0.25 parts by weight of a catalyst and 100 parts by weight of a filler;

[0078] Wherein, material A comprises the following components in parts by weight:

[0079] Castor oil polyol 90 parts by weight

[0080] Bio-based polyester polyol A1 10 parts by weight

[0081] 20 parts by weight of 1,3-propylene glycol;

[0082] The material B is a bio-based polyurethane prepolymer, wherein the mass percentage of NCO groups is 20%.

[0083] The preparation method of the polyurethane prepolymer comprises: reacting 10 parts by weight of castor oil polyol, 26 parts by weight of bio-based polyester polyol A1, 54 parts by weight of MDI and 10 parts by weight of carbodiimide-uretonimine modified MDI at 70° C. under nitrogen protection for 3.5 hours to obtain the bio-based polyurethane prepolymer;

[0084] The catalyst includes 0.05 parts by weight of bismuth neodecanoate and 0.2 parts by weight of zinc neodecanoate;

[0085] The filler is bio-based wood powder.

[0086] Example 4

[0087] A two-component solvent-free polyurethane resin is different from Example 1 only in that the amount of bio-based polyester alcohol A1 added in material A is 10 parts by weight, and other components, amounts and preparation methods are the same as those in Example 1.

[0088] Example 5

[0089] A two-component solvent-free polyurethane resin, which differs from Example 1 only in that the amount of bio-based polyester polyol A1 added in material A is 30 parts by weight, and other components, amounts and preparation methods are the same as those in Example 1.

[0090] Example 6

[0091] A two-component solvent-free polyurethane resin, which differs from Example 1 only in that bio-based polyurethane polyol A2 is used to replace bio-based polyurethane polyol A1 in material A and material B, and other components, amounts and preparation methods are the same as those in Example 1.

[0092] Comparative Example 1

[0093] A two-component solvent-free polyurethane resin, wherein Kolia GP-1000 (3 functionalities, 1000 molecular weight) is used to replace the castor oil polyol in material A, and other components, amounts and preparation methods are the same as those in Example 1.

[0094] Comparative Example 2

[0095] A composite material for preparing a two-component solvent-free polyurethane resin, wherein Huafeng Polyester PE-7018 is used to replace the bio-based polyester polyol A1 in material A and material B, and other components, amounts and preparation methods are the same as those in Example 1.

[0096] Application Example 1

[0097] A synthetic leather, the preparation method of which comprises: mixing material A and a catalyst in the two-component solvent-free polyurethane resin provided in Example 1 for 1 minute, adding filler (bio-based wood powder) and stirring for 5 minutes, and after stirring evenly, adding material B and mixing at room temperature for 15 seconds, and then evenly coating on the Huafeng waterborne polyurethane surface layer JF-PDY-851HY, foaming reaction at 100°C, laminating to a base fabric at maximum viscosity, and finally curing and forming at 150°C to obtain the synthetic leather.

[0098] Application Examples 2 to 6

[0099] A synthetic leather, which differs from Application Example 1 only in that the A material, B material, catalyst and filler in the two-component solvent-free polyurethane resin provided in Examples 2 to 6 are used to replace the A material, B material, catalyst and filler in the two-component solvent-free polyurethane resin provided in Example 1, and other conditions and steps are the same as those in Application Example 1.

[0100] Comparative Application Examples 1-2

[0101] A synthetic leather, which differs from Application Example 1 only in that the A material, B material, catalyst and filler in the two-component solvent-free polyurethane resin provided in Comparative Examples 1 to 2 are used to replace the A material, B material, catalyst and filler in the two-component solvent-free polyurethane resin provided in Example 1, and other conditions and steps are the same as those in Application Example 1.

[0102] Performance Test:

[0103] (1) Resilience: Fold a piece of synthetic leather with a size of 10 × 10 cm in half, press it with a 5 kg weight at 70 °C for 5 h, and then leave it for 1 h to observe the recovery of the crease.

[0104] (2) Peel strength: tested in accordance with GB / T 1040.3-2006.

[0105] (3) Biodegradability: The test was conducted in accordance with GB / T 19811-2005, with a test period of 12 weeks, and the degree of disintegration was calculated.

[0106] The synthetic leather obtained from Examples 1 to 6 and Comparative Application Examples 1 to 2 was tested according to the above test method. The test results are shown in Table 1:

[0107] Table 1

[0108]

[0109] It should be noted that the above-mentioned rebound performance can not only explain the rebound effect of the leather, but also explain the influence of the filler added to the resin on the reaction and maturation of the resin. The better the rebound resilience, the smaller the influence of the addition of the filler on the resin.

[0110] Specifically:

[0111] (1) According to the data of Application Examples 1 to 5, it can be seen that the synthetic leather prepared by the two-component solvent-free polyurethane resin prepared within the formula ratio range provided by the present invention has normal aging and good resilience, and also has extremely high physical properties (peel strength of not less than 60N / 2.5cm) and a biodegradability of not less than 90%;

[0112] From the comparison of the data of Application Example 6 and Application Example 1, it can be seen that the peel strength of the polyurethane further prepared by the bio-based polyester polyol made from succinic acid alone is lower than that of the polyurethane resin further prepared from the bio-based polyester polyol made from succinic acid and sebacic acid.

[0113] (2) From the data comparison between Application Example 1 and Comparative Application Example 1, it can be seen that the use of ordinary polyether polyols to replace vegetable oil polyols will lead to a decrease in the hydrophobic properties of the prepared polyurethane resin, which in turn leads to poor reaction maturation during the preparation of synthetic leather, poor recovery of synthetic leather, and a significant decrease in binding properties with the water-based surface layer.

[0114] (3) From the data comparison between Application Example 1 and Comparative Application Example 2, it can be seen that the use of ordinary polyester polyols to replace bio-based polyester polyols will lead to a significant decrease in the bonding properties between the adhesive layer and the water-based surface layer and the biodegradability of the synthetic leather.

[0115] The applicant declares that the present invention illustrates a hydroxy composition for preparing a two-component solvent-free polyurethane resin and its application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A two-component solvent-free polyurethane resin, characterized in that: The raw materials for preparing the two-component solvent-free polyurethane resin include material A, material B and filler; The A material includes a hydroxy compound; The hydroxy compound comprises the following components in parts by weight: Vegetable oil polyol A 70-90 parts by weight Bio-based polyester polyol A 10-30 parts by weight 1-20 parts by weight of chain extender; The functionality of the vegetable oil polyol A is not less than 2, and the functionality of the bio-based polyester polyol A is 2 to 3; The bio-based polyester polyol A is obtained by reacting bio-based succinic acid and bio-based sebacic acid with 1,3-propylene glycol in a mass ratio of 1.17:1; The B material includes a bio-based polyurethane prepolymer; The raw materials for preparing the bio-based polyurethane prepolymer include diisocyanate and bio-based polyol; The diisocyanate includes MDI and / or carbodiimide-uretonimine modified MDI; The mass percentage of NCO in the bio-based polyurethane prepolymer is 15-25%; The mass ratio of the A material to the B material is 100:(50~150).

2. The two-component solvent-free polyurethane resin according to claim 1, characterized in that: The vegetable oil polyol A includes any one of castor oil polyol, soybean oil polyol or palm oil polyol, or a combination of at least two of them.

3. The two-component solvent-free polyurethane resin according to claim 1, characterized in that: The bio-based polyester polyol A has a hydroxyl value of 28-112 mkgKOH / g.

4. The two-component solvent-free polyurethane resin according to claim 1, characterized in that: The chain extender includes C2~C12 small molecule diols.

5. The two-component solvent-free polyurethane resin according to claim 4, characterized in that: The C2-C12 small molecule diol includes any one of ethylene glycol, propylene glycol, butanediol or hexanediol, or a combination of at least two of them.

6. The two-component solvent-free polyurethane resin according to claim 1, characterized in that: The hydroxy compound is prepared according to the following preparation method, which comprises: mixing vegetable oil polyol A, bio-based polyester polyol A and a chain extender to obtain the hydroxy compound.

7. The two-component solvent-free polyurethane resin according to claim 1, characterized in that: The bio-based polyol includes vegetable oil polyol B and / or bio-based polyester polyol B.

8. The two-component solvent-free polyurethane resin according to claim 1, characterized in that: The raw materials for preparing the two-component solvent-free polyurethane resin also include any one of a catalyst, a foaming agent or silicone oil, or a combination of at least two of them.

9. The two-component solvent-free polyurethane resin according to claim 8, characterized in that: The catalyst includes a bismuth-zinc composite catalyst.

10. The two-component solvent-free polyurethane resin according to claim 1, characterized in that: The filler includes plant residues.

11. A synthetic leather, characterized in that: The synthetic leather comprises the two-component solvent-free polyurethane resin as described in any one of claims 1 to 10.

12. A method for preparing the synthetic leather as claimed in claim 11, characterized in that: The preparation method comprises: mixing material A and an optional catalyst in the two-component solvent-free polyurethane resin according to any one of claims 1 to 10, adding a filler for mixing, then adding material B for mixing, and then evenly coating the mixture on a surface layer for foaming reaction, laminating the mixture to a base fabric, and curing the mixture to obtain the synthetic leather.

13. The preparation method according to claim 12, characterized in that: The temperature of the foaming reaction is 80-130°C.

14. The preparation method according to claim 12, characterized in that: The foaming reaction time is 2 to 10 min.

15. The preparation method according to claim 12, characterized in that: The curing temperature is 100-160°C.

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