Polyurethane moisture-curing hot-melt coating adhesive and preparation method thereof

Abstract

The invention discloses a polyurethane moisture-curing hot-melt coating adhesive and a preparation method thereof, the preparation components of the polyurethane moisture-curing hot-melt coating adhesive comprise a block copolymer containing a soft segment, a hard segment and a transition segment, the soft segment comprises oligomer polyester and polyether, the hard segment comprises polyisocyanate or other chain extenders, and the transition segment comprises polyisocyanate or other chain extenders. And the transition section comprises thermoplastic polyurethane elastomer resin. The coating adhesive has the advantages of excellent initial adhesion, high curing speed, large later-stage curing force, uniform adhesive sample, good heat-conducting property, low-temperature resistance, high-temperature resistance, no yellowing in the later stage, no bubbles and the like, and overcomes the defects of small initial adhesion, long curing time, non-uniform adhesive sample, poor heat-conducting property, poor adaptability to low-temperature and high-temperature environments, easiness in yellowing in the later stage, low cost and the like of a common hot melt adhesive or low-end polyurethane. And bubbles are easy to generate after being heated.

Description

Technical Field

[0001] The invention relates to the technical field of adhesive preparation, and specifically provides a polyurethane moisture-curing hot-melt coating adhesive and a preparation method thereof. Background Art

[0002] PUR hot melt adhesive is different from traditional hot melt adhesive. It has the characteristics of both hot melt and reactive adhesives. During bonding, the adhesive is heated and melted into a fluid and applied. After the two adherends are bonded, the adhesive layer cools and condenses to obtain initial bonding strength. Afterwards, the active -NCO groups in the adhesive layer react with moisture in the air, moisture adsorbed on the surface of the adherend, and active hydrogen groups to produce chemical cross-linking and curing, generating a high molecular polymer with high cohesion, which significantly improves adhesion and heat resistance.

[0003] PUR hot melt adhesive has the characteristics of being solvent-free, having high initial adhesion, and being able to quickly position during assembly, as well as the properties of reactive adhesives such as water resistance, heat resistance, creep resistance, moisture resistance, and media resistance. Since its appearance in 1984, it has developed rapidly and has been widely used.

[0004] Covering and decorating irregularly shaped parts of furniture and decorative components involves applying coatings to non-bottle (irregular) surfaces of furniture or decorative pieces. The goal is to create a close fit on these uneven sides or ends, not only to prevent erosion from moisture, acids, alkalis, microorganisms, and pests, but also to highlight the contours of these areas. The covering process involves sequential pressing using a glue and pressing device tailored to the irregularly shaped surface. The most important requirement for covering is rapid curing between the substrate and the covering film, ensuring a dense and secure bond that meticulously captures the artistic beauty of these curved surfaces. Currently, few products on the market meet this requirement. Summary of the Invention

[0005] In view of the above problems, the present invention provides the following technical solutions: In one aspect, the present invention provides a polyurethane moisture-curing hot-melt coating adhesive, wherein the preparation components of the polyurethane moisture-curing hot-melt coating adhesive include a block copolymer containing a soft segment, a hard segment and a transition segment, wherein the soft segment component includes an oligomer polyester or a polyether, the hard segment component includes a polyisocyanate or other chain extender, and the transition segment component includes a thermoplastic polyurethane elastomer resin.

[0006] Among them, the oligomer polyester and polyether are: polyisophthalic acid-1,6 hexanediol-neopentyl glycol ester, copolyacid copolyester diol ester, polycarbonate polyether diol; Polyisocyanate or other chain extender is: diphenylmethane-4,4-diisocyanate.

[0007] The soft segment, hard segment, and transition segment of the coating rubber of the present invention are interconnected, with complementary properties, collectively forming the product's superior structure. Due to the thermodynamic incompatibility of the three segments, they undergo microscopic phase separation, with phase regions and microphase regions existing within them. Ether, urea, and urethane groups present in the polyurethane generate hydrogen bonds, with the thermoplastic polyurethane elastomer contributing significantly to the product's flexibility, while urea and urethane bonds contribute significantly to the product's hard segment. The hard segment, soft segment, and thermoplastic polyurethane elastomer are cross-linked and complementary, resulting in the product's unique flexibility and wide range of physical properties. The product's superior performance is primarily due to the formation of microphase regions, followed over time by hydrogen bonding between the hard and soft segments.

[0008] Furthermore, the raw material components of the polyurethane coating glue include: 1 to 20 parts by mass of poly(1,6-hexanediol adipate), 1 to 20 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol, 5 to 25 parts of copolyester copolyester, 10 to 25 parts of polycaprolactone diol, 5 to 20 parts of thermoplastic polyurethane elastomer, 10 to 30 parts of polycarbonate polyether diol, 0.5 to 5 parts of antioxidant, and 7 to 10 parts of diphenylmethane-4,4-diisocyanate.

[0009] Furthermore, the raw material components of the polyurethane coating glue include: 5 to 15 parts by mass of poly(1,6-hexanediol adipate), 10 to 15 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol, 10 to 25 parts of copolyester copolyester, 10 to 25 parts of polycaprolactone diol, 5 to 10 parts of thermoplastic polyurethane elastomer, 10 to 20 parts of polycarbonate polyether diol, 0.5 to 5 parts of antioxidant, and 7 to 10 parts of diphenylmethane-4,4-diisocyanate.

[0010] By adjusting the proportions of the above components, the technical effect produced is: the 180° peeling force of the polyurethane coating adhesive reaches 50-60N / 25mm, and the open time is 100-150 seconds.

[0011] Furthermore, the raw material components of the polyurethane coating glue include: 10 parts by mass of poly(1,6-hexanediol adipate), 10 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol, 20 parts of copolyester copolyester, 20 parts of polycaprolactone diol, 10 parts of thermoplastic polyurethane elastomer, 20 parts of polycarbonate polyether diol, 1 part of antioxidant, and 8 parts of diphenylmethane-4,4-diisocyanate.

[0012] By adjusting the proportions of the above components, the technical effect produced is: the 180° peeling force of the polyurethane coating adhesive reaches 80-100N / 25mm, and the open time is 100-150 seconds.

[0013] In another aspect, the present invention provides a method for preparing a polyurethane moisture-curing hot-melt coating adhesive, wherein the method comprises the following steps: Weigh polyester polyol and tackifying resin and add them into the reaction kettle, heat it to 90℃~120℃ under the pressure of -0.08MPa~-0.1MPa, melt it, dehydrate it until the liquid material has no bubbles escaping, cool it to 80℃~100℃, then add diphenylmethane-4,4-diisocyanate and heat it to 110℃~120℃ for polymerization reaction for 1~2h, then filter and discharge it while hot under nitrogen protection to obtain the polyurethane moisture-curing hot-melt coating adhesive.

[0014] Furthermore, the polyester polyol is polyadipate-1,6-hexanediol ester diol, polycaprolactone diol, and polycarbonate polyether diol, and the mass proportions are 1-20 parts, 10-25 parts, and 10-30 parts respectively.

[0015] Furthermore, the tackifying resin is polyisophthalic acid-1,6-hexanediol-neopentyl glycol ester, copolyester diol ester, and thermoplastic polyurethane elastomer, and the mass proportions are 1-20 parts, 5-25 parts, 10-25 parts, and 5-20 parts respectively.

[0016] Furthermore, the components added to the reactor in the preparation method also include antioxidants, with the mass ratio being 0.5 to 5 parts.

[0017] Furthermore, the mass ratio of the diphenylmethane-4,4-diisocyanate is 7 to 10 parts.

[0018] Furthermore, the residual isocyanate molar percentage content reaches 0.5% to 2%.

[0019] Compared with the prior art, the polyurethane moisture-curing hot-melt coating adhesive and preparation method of the present invention have the following outstanding beneficial effects: The present invention provides a highly adaptable polyurethane coating PUR adhesive. The coating adhesive has the advantages of excellent initial adhesion, fast curing speed, strong late curing strength, uniform adhesive sample, good thermal conductivity, resistance to low and high temperatures, no yellowing in the late stage, and no bubbles. It overcomes the defects of general hot melt adhesives or low-end polyurethanes, such as low initial adhesion, long curing time, uneven adhesive sample, poor thermal conductivity, poor adaptability to low and high temperature environments, easy yellowing in the late stage, and easy generation of bubbles when heated. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below with reference to the embodiments.

[0021] control group EVA woodworking coating hot melt adhesive: composed of the following raw materials in parts by weight: ethylene vinyl acetate copolymer EVA 40-70 parts, tackifying resin 20-30 parts, wax 5-20 parts, antioxidant 0.5-2 parts, small molecule oligomer 0-10 parts; Add the above raw materials into the reactor, heat to 90-100℃ while stirring, and the stirring speed is 20-30r / min. Put the evenly mixed materials into the twin-screw extruder for extrusion operation. The extruded product is cooled and granulated to obtain EVA woodworking coating adhesive. Example 1

[0022] A highly adaptable polyurethane coating PUR adhesive is composed of the following raw materials in parts by mass: poly (1,6-hexanediol adipate), poly (1,6-hexanediol isophthalate-neopentyl glycol), copolyester copolyester diol, polycaprolactone diol, thermoplastic polyurethane elastomer, polycarbonate polyether diol, antioxidant, and diphenylmethane-4,4-diisocyanate, with the mass proportions being 10 parts, 15 parts, 15 parts, 20 parts, 20 parts, 10 parts, 0.5 parts, and 10 parts, respectively; 10 parts of poly(1,6-hexanediol adipate), 15 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol, 15 parts of copolyester copolyester, 20 parts of polycaprolactone diol, 20 parts of thermoplastic polyurethane elastomer, 10 parts of polycarbonate polyether diol, and 0.5 parts of antioxidant are added into a reactor, heated to 90° C. under a pressure of -0.08 MPa for melting, dehydrated until the liquid material has no bubbles escaping, cooled to 80° C., and then 10 parts of diphenylmethane-4,4-diisocyanate are added and heated to 110° C. for polymerization reaction for 1 hour. Then, the mixture is filtered and discharged while hot under nitrogen protection to obtain a polyurethane moisture-curing hot-melt coating adhesive. Example 2

[0023] A highly adaptable polyurethane coating PUR adhesive is composed of the following raw materials in parts by mass: poly (1,6-hexanediol adipate), poly (1,6-hexanediol isophthalate-neopentyl glycol), copolyester copolyester, polycaprolactone diol, thermoplastic polyurethane elastomer, polycarbonate polyether diol, antioxidant, and diphenylmethane-4,4-diisocyanate, with the mass proportions being 15 parts, 15 parts, 20 parts, 15 parts, 10 parts, 15 parts, 0.5 parts, and 10 parts, respectively; 15 parts of poly(1,6-hexanediol adipate), 15 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol, 20 parts of copolyester copolyester, 15 parts of polycaprolactone diol, 10 parts of thermoplastic polyurethane elastomer, 15 parts of polycarbonate polyether diol, and 0.5 parts of antioxidant were added into a reactor, heated to 100° C. under a pressure of -0.1 MPa, melted, and dehydrated until no bubbles escaped from the liquid, cooled to 100° C., and then 10 parts of diphenylmethane-4,4-diisocyanate were added and heated to 120° C. for polymerization reaction for 2 hours. Then, the mixture was filtered and discharged while hot under nitrogen protection to obtain a polyurethane moisture-curing hot-melt coating adhesive. Example 3

[0024] A highly adaptable polyurethane coating PUR adhesive is composed of the following raw materials in parts by mass: poly (1,6-hexanediol adipate), poly (1,6-hexanediol isophthalate-neopentyl glycol), copolyester copolyester diol, polycaprolactone diol, thermoplastic polyurethane elastomer, polycarbonate polyether diol, antioxidant, and diphenylmethane-4,4-diisocyanate, with the mass proportions being 10 parts, 12 parts, 20 parts, 20 parts, 10 parts, 20 parts, 1 part, and 8 parts, respectively; 10 parts of poly(1,6-hexanediol adipate), 12 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol, 20 parts of copolyester copolyester, 20 parts of polycaprolactone diol, 10 parts of thermoplastic polyurethane elastomer, 20 parts of polycarbonate polyether diol and 1 part of antioxidant were added into a reactor, heated to 90°C under a pressure of -0.09 MPa for melting and dehydration until no bubbles escaped from the liquid, cooled to 90°C, and then 8 parts of diphenylmethane-4,4-diisocyanate were added and heated to 115°C for polymerization reaction for 1.5 hours. Then, the mixture was filtered and discharged while hot under nitrogen protection to obtain a polyurethane moisture-curing hot-melt coating adhesive.

[0025] Example 4 Performance Measurement of PUR Adhesive for Polyurethane Coating The polyurethane coating PUR adhesive products described in Examples 1-3 and the comparative example were subjected to performance testing. The specific testing method is as follows: The test was conducted using the test method specified in GB / T 2790-1995 on polyurethane (PUR) adhesive specimens for polyurethane coating. Peel strength is a key method for evaluating adhesive bonding performance. Peel strength is the maximum load per unit bond area and is the force required per unit specimen width to separate the bonded surface.

[0026] The measurement results are shown in the following table:

[0027] The above test results demonstrate that the polyurethane coating adhesive prepared using the technical solution of the present invention exhibits excellent performance. The adhesives prepared in Examples 1-3 of the present invention exhibit significantly higher initial tack and peel strength than the comparative examples, and exhibit excellent bond strength and heat resistance, meeting the current requirements of the furniture market and possessing broad prospects for development in the adhesive industry. Furthermore, the test results demonstrate that the raw material ratio significantly influences product performance.

[0028] The embodiments described above are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A polyurethane moisture-curing hot-melt coating adhesive, characterized in that: The preparation components of the polyurethane moisture-curing hot-melt coating adhesive include a block copolymer containing a soft segment, a hard segment and a transition segment, wherein the soft segment component includes an oligomer polyester or a polyether, the hard segment component includes a polyisocyanate or other chain extender, and the transition segment component includes a thermoplastic polyurethane elastomer resin; Among them, the oligomer polyester and polyether are: polyisophthalic acid-1,6 hexanediol-neopentyl glycol ester, copolyacid copolyester diol ester, polycarbonate polyether diol; The polyisocyanate is: diphenylmethane-4,4-diisocyanate.

2. The polyurethane moisture-curing hot melt coating adhesive according to claim 1, characterized in that: The raw material components of the polyurethane coating glue include, by mass, 1 to 20 parts of poly(1,6-hexanediol adipate) diol, 1 to 20 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol ester, 5 to 25 parts of copolyester copolyester diol ester, 10 to 25 parts of polycaprolactone diol, 5 to 20 parts of thermoplastic polyurethane elastomer, 10 to 30 parts of polycarbonate polyether diol, 0.5 to 5 parts of antioxidant, and 7 to 10 parts of diphenylmethane-4,4-diisocyanate.

3. The polyurethane moisture-curing hot melt coating adhesive according to claim 2, characterized in that: The raw material components of the polyurethane coating glue include, by mass, 5 to 15 parts of poly(1,6-hexanediol adipate), 10 to 15 parts of poly(1,6-hexanediol isophthalate)-neopentyl glycol, 10 to 25 parts of copolyester copolyester diol, 10 to 25 parts of polycaprolactone diol, 5 to 10 parts of thermoplastic polyurethane elastomer, 10 to 20 parts of polycarbonate polyether diol, 0.5 to 5 parts of antioxidant, and 7 to 10 parts of diphenylmethane-4,4-diisocyanate.

4. The polyurethane moisture-curing hot melt coating adhesive according to claim 3, characterized in that: The raw material components of the polyurethane coating glue include, by mass, 10 parts of poly(1,6-hexanediol adipate) diol, 10 parts of poly(1,6-hexanediol isophthalate) neopentyl glycol ester, 20 parts of copolyester copolyester diol, 20 parts of polycaprolactone diol, 10 parts of thermoplastic polyurethane elastomer, 20 parts of polycarbonate polyether diol, 1 part of antioxidant, and 8 parts of diphenylmethane-4,4-diisocyanate.

5. A method for preparing a polyurethane moisture-curing hot-melt coating adhesive, characterized in that: The method is implemented as follows: Add polyester polyol and tackifying resin into a reaction kettle, heat to 90°C to 120°C under a pressure of -0.08MPa to -0.1MPa, melt and dehydrate until the liquid material has no bubbles escaping, cool to 80°C to 100°C, then add diphenylmethane-4,4-diisocyanate and heat to 110°C to 120°C for polymerization reaction for 1 to 2 hours, then filter and discharge the material while hot under nitrogen protection to obtain the polyurethane moisture-curing hot-melt coating adhesive.

6. The method for preparing a polyurethane moisture-curing hot-melt coating adhesive according to claim 5, characterized in that: The polyester polyol is polyadipate-1.6 hexanediol ester diol, polycaprolactone diol, and polycarbonate polyether diol, and the mass proportions thereof are 1-20 parts, 10-25 parts, and 10-30 parts respectively.

7. The method for preparing a polyurethane moisture-curing hot-melt coating adhesive according to claim 5, characterized in that: The tackifying resin is polyisophthalic acid-1.6 hexanediol-neopentyl glycol ester, copolyester copolyester diol ester, and thermoplastic polyurethane elastomer, and the mass proportions are 1-20 parts, 5-25 parts, 10-25 parts, and 5-20 parts respectively.

8. The method for preparing a polyurethane moisture-curing hot-melt coating adhesive according to claim 6 or 7, characterized in that: The components added to the reactor in the preparation method also include antioxidants, with a mass ratio of 0.5 to 5 parts.

9. The method for preparing a polyurethane moisture-curing hot-melt coating adhesive according to claim 8, characterized in that: The mass ratio of the diphenylmethane-4,4-diisocyanate is 7 to 10 parts.

10. The method for preparing a polyurethane moisture-curing hot-melt coating adhesive according to claim 5, characterized in that: The completion standard of the polymerization reaction in the method is that the residual isocyanate molar percentage content reaches 0.5% to 2%.

Images