WO2019144420A1

WO2019144420A1 - Hot-melt adhesive used for out-side membrane transfer printing technology and preparation method thereof

Info

Publication number: WO2019144420A1
Application number: PCT/CN2018/074581
Authority: WO
Inventors: 宋攀可; 张春; 白永平; 程宝强
Original assignee: 佛山市加恩新材料有限公司
Priority date: 2018-01-23
Filing date: 2018-01-30
Publication date: 2019-08-01
Also published as: CN108148533A; CN108148533B

Abstract

A hot-melt adhesive used for out-side membrane transfer technology, comprising the following substances in mass fraction: a basic resin 30-40%; a tackifier 30-40%; a viscosity modifier 5-10%; an antioxidant 5-10%; and an organic solvent 25-50%; the basic resin is synthesized from a modified chloroacetate resin and saturated polyester under the action of a diisocyanate. The hot-melt adhesive in the present invention is thermoplastic, while a curing agent does not need to be added, a finished product has stable properties, storage period is long, and peel strength is high, thus being suitable for flexible and smooth membranes in an out-side model decoration (OMD) process; the preparation method is simple and easy, and is suitable for mass production.

Description

[Correction according to Rule 26 02.04.2018] Hot melt adhesive for film transfer technology and preparation method thereof

Technical field

The invention relates to the field of hot melt adhesives, in particular to a hot melt adhesive for use in an extra-membrane transfer technology and a preparation method thereof.

Background technique

OMD (Out-side Model Decoration) is a surface decoration technology that uses a high-pressure vacuum transfer to directly coat a graphic onto a plastic or metal surface to form a three-dimensional coating after printing the pattern on a transparent film. The transparent film is the carrier of the graphic. When transferring the pattern, the OMD transfer film is first softened and softened at about 150 °C, and then tightly adsorbed to the surface of the object for about 10 to 15 seconds under the reduced pressure of the vacuum pump. After the bonding is completed, the substrate is peeled off, and the pattern remains on the surface of the object. .

OMD transfer film is the core of the external transfer technology. Different functional layers on the transfer film have different functions. The adhesive layer provides the bonding force between the pattern layer and the surface of the object. The properties of the hot melt adhesive used in the adhesive layer determine the pattern layer. Whether it is durable and durable, whether the decorated object can meet the requirements for use. A related patent discloses an adhesive used in thermal transfer. For example, the patent No. CN201210436409.9 discloses a glass-based thermal transfer adhesive prepared by using an epoxy resin as a main component. Patent No. CN201210436137.2 discloses a thermal transfer adhesive prepared by using polyurethane and acrylate as a curing system, a thermal transfer film and a thermal transfer method; Patent No. CN201310194469.9 discloses an epoxy resin And polyurethane composite thermal transfer adhesive and preparation method thereof; patent No. CN201310194492.8 discloses an acrylic resin thermal transfer adhesive and a preparation method thereof. The above patents all relate to the adhesive used in thermal transfer, but all of them use a curing agent, which is a thermosetting adhesive. When such an adhesive is used, a curing agent is added to the adhesive and a transfer film is prepared, which causes unstable transfer film performance, short storage period, and poor adaptability. In a high room temperature environment, the activity of the curing agent is enhanced, which tends to cause the adhesive to cure in advance, and the transfer film is scrapped. In addition, the patent No. CN200910099377.6 discloses a polyurethane hot melt adhesive for high-grade lining cloth and a preparation method thereof; and the patent No. CN201310277072.6 discloses a preparation of a composite hot melt adhesive for polyvinyl chloride decorative board. The method of CN201510497729.9 discloses a method for preparing a modified polyester hot melt adhesive and a film thereof. Patent No. CN201710451041.6 discloses a polyester amide hot melt adhesive and a preparation method thereof. OMD has specific process parameters, the transfer temperature is 120 ~ 150 ° C, the curing temperature is 60 ~ 100 ° C, the transfer time is 20 ~ 40s, the transfer pressure is the air source pressure 8Kg / m ² , the above patent belongs to the thermoplastic heat Melt, but the application is different, the thermodynamic index of the hot melt adhesive does not match the OMD process. Moreover, the materials decorated by the OMD process are various. The polyester hot melt adhesives mentioned in some of the above patents are only suitable for products with rough surface such as cloth and wood, and have insufficient surface bonding strength for low surface energy. Therefore, it is also necessary to develop a hot melt adhesive suitable for the OMD process.

Summary of the invention

The object of the present invention is to provide a hot melt adhesive for film transfer printing technology, which is a thermoplastic adhesive, has wide application range, high peel strength and is suitable for OMD process; the preparation process is simple and easy, and is suitable for Mass production.

A hot melt adhesive for use in an off-film transfer technique, comprising the following mass fractions:

Wherein, the basic resin is synthesized by a modified chloroacetate resin and a saturated polyester under the action of a diisocyanate.

In some embodiments, the substance for synthesizing the base resin is a diisocyanate, a modified chloroacetate resin, and a saturated polyester, and the mass fraction ratio of the three is from 1 to 2:2 to 3:5 to 7.

In some embodiments, the modified chloroacetate resin is obtained by reacting N-2-aminoethyl-2-hydroxypropionamide with a ternary chloroacetate resin;

The N-2-aminoethyl-2-hydroxypropionamide is composed of the following mass fraction ratio substances.

Lactic acid 45 to 50%;

Ethylenediamine 50 to 55%.

In some embodiments, the diisocyanate is in toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, lysine diisocyanate One or more.

In some embodiments, the ternary chloroacetate resin is a terpolymer of vinyl acetate, vinyl chloride, and maleic anhydride; the mass fraction of the three is

Vinyl acetate 13-15%;

Vinyl chloride 81～84%

Maleic anhydride 1 to 6%.

In some embodiments, the saturated polyester is a high molecular polymer obtained by dehydration condensation reaction of a dihydric alcohol and a dibasic acid, and the saturated polyester has a molecular weight of 10,000 to 50,000; One or more of an alcohol, propylene glycol, and butylene glycol; the dibasic acid is one or more of terephthalic acid, isophthalic acid, and phthalic acid.

The invention also discloses a method for preparing the above hot melt adhesive, comprising:

Step (1), placing the basic resin and the organic solvent in a container with a stirring device, controlling the temperature at 30 to 35 ° C, stirring and dissolving;

Step (2), sequentially adding a tackifier, a viscosity modifier and an antioxidant, heating to 60-80 ° C, sealing the container, stirring for 30 to 40 minutes;

Step (3), stop heating, keep warm for 30 minutes, let it cool naturally to room temperature.

In some embodiments, the method of preparing the base resin comprises:

Step A, the saturated polyester is dissolved in an organic solvent, wherein the mass fraction of the saturated polyester is 40 to 50%, and the mass fraction of the organic solvent is 50 to 60%;

Step B, adding modified chloroacetate resin and diisocyanate, maintaining the reaction temperature in a four-necked bottle at 60-80 ° C, and reacting for 2 hours.

In some embodiments, the method for preparing the modified chloroacetate resin comprises:

Step a, weigh the appropriate amount of lactic acid and ethylenediamine in a reaction vessel, and slowly react for 30 minutes at -5 ° C. When the reactants are converted into a light yellow oily liquid, the reaction is placed in an oven at 60 ° C to dry. , obtaining N-2-aminoethyl-2-hydroxypropionamide;

Step b, the ternary chloroacetate resin is dissolved in an organic solvent, wherein the mass fraction of the ternary chloroacetate resin is 20-30%, and the mass fraction of the organic solvent is 70-80%;

Step c, adding N-aminoethyl-2-hydroxypropionamide corresponding to 5% to 8% by mass of the ternary chloroacetate resin in the solution of step b, adding a catalytic amount, and reacting for 1 hour in a four-necked bottle The reaction temperature is 105 to 120 ° C, and the reactant is taken out and dried in an oven to remove the organic solvent for use.

In some embodiments, the catalyst is from 1 to 3% sodium hypophosphite.

The beneficial effects are as follows: 1. The hot melt adhesive is thermoplastic, does not need to add a curing agent, has stable product properties and long storage; 2. high peel strength, suitable for flexible and smooth film of OMD process; 3. simple preparation method Easy to implement, suitable for large-scale production.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a process for synthesizing the modifier N-2-aminoethyl-2-hydroxypropionamide (NHPA) in the present invention.

Figure 2 is a schematic diagram of the synthesis of a base resin in the present invention.

Fig. 3 is a structural diagram of a molecular chain of a modified chloroacetate resin and a molecular chain of a saturated polyester grafted by a diisocyanate.

Among them, a represents ethylenediamine and lactic acid to produce EHPA, and b represents EHPA and lactic acid to produce by-products.

Detailed ways

The technical solution of the present invention will be described below with reference to the accompanying drawings.

The tackifier is one or more of rosin, modified rosin, C5 petroleum resin, C9 petroleum resin, and terpene resin for increasing the bonding strength.

The viscosity modifier is one or more of paraffin wax, microcrystalline wax, synthetic wax (PE or PP), and fossa wax.

The antioxidant is pentaerythritol ester, n-octadecyl propionate, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, tris(nonylbenzene) Base) phosphite and the like.

The organic solvent is one or more of methyl ethyl ketone, cyclohexanone, acetone, toluene, xylene, ethyl acetate, butyl acetate, and isopropyl acetate.

There are a large number of ester bonds in the main chain of saturated polyester. The ester bond is easily hydrolyzed and broken under the acid-base environment and ultraviolet light, resulting in poor acid and alkali resistance of the polyester hot melt adhesive. The modified polyester has chloroacetate resin. The interpenetrating network structure formed by the saturated polyester, the chloroacetic resin has good acid and alkali resistance, and the molecular weight has a wrap-around effect on the ester bond, thereby protecting the prepared hot melt adhesive. Acid and alkali resistance and weather resistance.

Lactic acid 45 to 50%;

Ethylenediamine 50 to 55%.

As shown in Fig. 1, amidation reaction of a primary amino group in ethylenediamine with a carboxyl group in lactic acid to prepare a N-2-amino group having two different functional groups of an amine group (-NH2) and a hydroxyl group (-OH) is prepared. Ethyl-2-hydroxypropionamide (NHPA). At the same time, the ternary chloroacetate resin has a carboxyl group (-COOH) in its main chain, and the amidation reaction activity is higher than that of the esterification reaction, and the modifier NHPA is reacted with the ternary chloroacetate resin under certain conditions. Its -COOH is converted to -OH. In the chemical reaction of ethylenediamine and lactic acid, there are two reaction routes, wherein a means ethylenediamine and lactic acid to produce EHPA, and b means that EHPA reacts with lactic acid to produce by-products. If too many by-products, EHPA is less. Will cause insufficient modification of the chloroacetate resin. Therefore, preferably, when synthesizing NHPA, the mass fraction of ethylenediamine is greater than the mass fraction of lactic acid, which contributes to the reaction in the direction in which NHPA is formed.

As shown in Fig. 2 and Fig. 3, both the modified chloroacetate resin and the saturated polyester have a hydroxyl group (-OH), which can react with the diisocyanate to pass the molecular chain of the chloroacetate resin and the molecular chain of the saturated polyester. The isocyanates are grafted together. This method grafts the polyfunctional chloroacetic resin onto the saturated polyester molecular chain, so that the saturated polyester contains more functional groups, which improves the adaptability of the hot melt adhesive to the bonding material.

Vinyl acetate 13-15%;

Vinyl chloride 81～84%

Maleic anhydride 1 to 6%.

Chloroacetate resin has excellent adhesion to metals, especially aluminum, and has excellent adhesion to PVC products, paper, fiber, glass, ceramic tile, sandstone and wood.

In some embodiments, the saturated polyester is a high molecular polymer obtained by dehydration condensation reaction of a dihydric alcohol and a dibasic acid, the saturated polyester having a molecular weight of 10,000 to 50,000; the glycol is ethylene glycol. One or more of propylene glycol and butylene glycol; the dibasic acid is one or more of terephthalic acid, isophthalic acid and phthalic acid.

The dibasic acid of the synthetic polyester has a benzene ring to provide molecular cohesion.

The invention also discloses a method for preparing a hot melt adhesive as described above, comprising:

In some embodiments, the method of preparing the base resin comprises:

The four-necked flask also has a condensing unit and a stirring device.

In the step a, since the reaction of ethylenediamine and lactic acid is very active, a side reaction occurs at normal temperature, so lowering the reaction temperature is advantageous for moving the reaction to the target product. In the step c, the four-necked flask was provided with a distillation apparatus and a stirring apparatus; it was dried in an oven to remove unreacted ethylenediamine impurities.

In some embodiments, the catalyst is from 1 to 3% sodium hypophosphite.

Sodium hypochlorite is an amidation catalyst and the reaction is an amidation reaction.

The technical solution of the present invention will be further described below by way of specific examples.

Example 1

1. Prepare the basic resin as follows:

Step 1. The reactant is weighed according to the mass fraction of 50% lactic acid and 50% ethylenediamine, and placed in a reaction vessel, and slowly reacted in a refrigerator at -5 ° C for 30 minutes. When the reactant is converted into a pale yellow oily liquid, The reaction was dried in an oven at 60 ° C to remove unreacted ethylenediamine to give N-2-aminoethyl-2-hydroxypropanamide (NHPA).

Step 2: Prepare an organic solvent with a mass fraction of methyl butanone: toluene = 1:1, and use a ternary chloroacetate resin (from 13% by mass of vinyl acetate, 81% of vinyl chloride, and 6% of Malay). Anhydride synthesis) is prepared by dissolving in an organic solvent to prepare a solution, wherein the ternary chloroacetate resin is 20%, and the solvent is 80%.

Step 3, adding NHPA equivalent to 5% by mass of ternary chloroacetate resin to the solution of step 2, adding 1% catalytic amount of sodium hypophosphite, and reacting for 1 hour in a four-necked flask with a distillation device and a stirring device. The reaction temperature was 105 ° C, and the reactant was taken out and dried in an oven to remove the solvent.

Step 4. Prepare a solution by dissolving the saturated polyester in an organic solvent, wherein the saturated polyester is 40% and the organic solvent is 60%.

Step 5, adding the above modified chloroacetate resin and diisocyanate, the mass fraction ratio is diisocyanate: modified chloroacetate resin: saturated polyester = 1:3:6, controlled reaction temperature is 80 ° C, with a condensing device The reaction was carried out for 2 hours in a four-necked flask with a stirring device to obtain a copolymer of a saturated polyester and a chloroacetic resin.

2. Prepare hot melt adhesive according to the following formula:

The preparation process is as follows:

Step (1), the basic resin and the organic solvent are placed in a container equipped with a stirring device according to the above formula, and the temperature is controlled at 35 ° C, and stirred to dissolve.

Step (2), adding rosin, modified rosin, paraffin, pentaerythritol ester in turn, heating to 80 ° C, sealing the container, and stirring for 30 minutes.

Step (3), terminate the heating device, keep it for 30 minutes, and let it cool to room temperature naturally.

Example 2

1. Prepare the basic resin as follows:

Step 1. The reactant is weighed according to the mass fraction of 45% lactic acid and 55% ethylenediamine, and placed in a reaction vessel, and slowly reacted in a refrigerator at -5 ° C for 30 minutes, when the reactant is converted into a pale yellow oily liquid. The reaction was dried in an oven at 60 ° C to remove unreacted ethylenediamine to give N-2-aminoethyl-2-hydroxypropanamide (NHPA).

Step 2: Prepare the solvent with a mass fraction of cyclohexanone:acetone=1:1, and synthesize the ternary chloroacetate resin (combined by 15% by mass of vinyl acetate, 84% of vinyl chloride and 1% of maleic anhydride). Preparing a solution in a solvent, wherein the ternary chloroacetate resin is 30% and the solvent is 70%.

Step 3, adding 8% by mass of NHPA equivalent to ternary chloroacetate resin to the solution of step 2, adding 2% catalytic amount of sodium hypophosphite, and reacting for 1 hour in a four-necked flask with a distillation device and a stirring device. The reaction temperature was maintained at 105 ° C, and the reactant was taken out and dried in an oven to remove the solvent.

Step 4. Prepare a solution by dissolving a saturated polyester in a solvent, wherein the saturated polyester is 40% and the organic solvent is 60%.

Step 5, adding the above modified chloroacetate resin and diisocyanate, the mass fraction ratio is diisocyanate: modified chloroacetate resin: saturated polyester = 2:3:5, controlled reaction temperature is 60 ° C, with a condensing device The reaction was carried out for 2 hours in a four-necked flask with a stirring device to obtain a copolymer of a saturated polyester and a chloroacetic resin.

2. Prepare hot melt adhesive according to the following formula:

The preparation process is as follows:

Step (1), the basic resin and the solvent are placed in a container with a stirring device according to the above formula, and the temperature is controlled at 30 ° C, and the mixture is stirred and dissolved.

Step (2), sequentially adding C5 petroleum resin, microcrystalline wax, n-stearyl alcohol propionate, heating to 60 ° C, sealing the container, and stirring for 40 minutes.

Example 3

1. Prepare the basic resin as follows:

Step 2: The solvent is prepared by mass ratio of xylene and ethyl acetate = 1:1.5, and the ternary chloroacetate resin (combined by 14% by mass of vinyl acetate, 83% of vinyl chloride and 3% of maleic anhydride) Preparing a solution in a solvent, wherein the ternary chloroacetate resin is 20% and the solvent is 80%.

Step 3, adding NHPA equivalent to 5% by mass of ternary chloroacetate resin to the solution of step 2, adding 3% catalytic amount of sodium hypophosphite, and reacting for 1 hour in a four-necked flask with a distillation device and a stirring device. The reaction temperature was 120 ° C, and the reactant was taken out and dried in an oven to remove the solvent.

Step 4. Prepare a solution by dissolving the saturated polyester in the solvent, wherein the saturated polyester is 50% and the organic solvent is 50%.

Step 5, adding the above modified ternary chloroacetate resin and diisocyanate, the mass ratio of which is diisocyanate: modified chloroacetate resin: saturated polyester = 1:2:7, controlled reaction temperature is 80 ° C, with condensation The apparatus was reacted in a four-necked bottle of the stirring device for 2 hours to obtain a copolymer of a saturated polyester and a chloroacetic resin.

2. Prepare hot melt adhesive according to the following formula:

The preparation process is as follows:

Step (1), the basic resin and the solvent are placed in a container with a stirring device according to the above formula, and the temperature is controlled at 35 ° C, and the mixture is stirred and dissolved.

Step (2), sequentially adding C9 petroleum tree, synthetic wax, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, heating to 60 ° C, sealing the container, stirring 40 minutes.

Example 4

1. Prepare the basic resin as follows:

Step 2. Prepare the solvent by mass ratio of butyl acetate and isopropyl acetate = 1:2, and ternary chloroacetate resin (from 14% by mass of vinyl acetate, 82% of vinyl chloride and 4% of Malay) Anhydride synthesis) is prepared by dissolving in a solvent to prepare a solution, wherein the ternary chloroacetate resin is 25% and the solvent is 75%.

Step 3, adding NHPA equivalent to 5% by mass of ternary chloroacetate resin to the solution of step 2, adding 2% catalytic amount of sodium hypophosphite, and reacting for 1 hour in a four-necked flask with a distillation device and a stirring device. The reaction temperature was 115 ° C, and the reactant was taken out and dried in an oven to remove the solvent.

Step 4. Prepare a solution by dissolving the saturated polyester in the solvent, wherein the saturated polyester is 45% and the organic solvent is 55%.

Step 5, adding the above modified chloroacetate resin and diisocyanate, the mass ratio of which is diisocyanate: modified chloroacetate resin: saturated polyester = 1:3:6, controlled reaction temperature is 80 ° C, with a condensation device and The reaction was carried out for 2 hours in a four-necked bottle of a stirring device to obtain a copolymer of a saturated polyester and a chloroacetic resin.

2. Prepare hot melt adhesive according to the following formula:

The preparation process is as follows:

Step (2), sequentially adding terpene resin, fossa wax, and tris(nonylphenyl) phosphite, heating to 60 ° C, sealing the container, and stirring for 30 minutes.

Performance test experimental data

1, hot melt adhesive thermodynamic performance test

Test method: The hot melt adhesive was characterized by DSC and TG, and the results are shown in Table 1.

Table 1 Thermowell performance test results of hot melt adhesive

实施例Example	玻璃化温度(℃)Glass transition temperature (°C)	软化温度(℃)Softening temperature (°C)	分解温度(℃)Decomposition temperature (°C)
对比例0 Comparative ratio 0	15.515.5	80.280.2	334.0334.0
实施例1Example 1	38.338.3	122.6122.6	376.3376.3
实施例2Example 2	40.540.5	125.4125.4	384.5384.5
实施例3Example 3	39.639.6	120.7120.7	379.6379.6
实施例4Example 4	37.237.2	118.7118.7	374.2374.2

The comparative example 0 is an unmodified saturated resin. From the data point of view, the glass transition temperature of the unmodified saturated resin is low, the performance of the prepared transfer film is unstable, and it may be softened in advance in a high temperature working environment. , affecting the process. It can be seen from the data of Examples 1 to 4 that, after the above modified resin, the glass transition temperature is increased to 37 to 40 ° C, the stability of the transfer film is improved, and the softening temperature is increased to 118 to 122 ° C, which is consistent with this temperature. The operating temperature of the external transfer, and the decomposition temperature is increased from 334 ° C to 374 ~ 384 ° C, improving the heat resistance of the hot melt adhesive.

2, peel strength test

Test method: The hot melt adhesive was tested according to the 180° peel strength test standard ISO 8510-2-2006, and the results are shown in the table.

Table 2 Hot melt adhesive glass strength test results

(V0 represents Comparative Example 0, V1 represents Embodiment 1, V2 represents Embodiment 2, V3 represents Embodiment 3, and V4 represents Embodiment 4.)

The comparative example 0 is an unmodified saturated polyester. From the peeling strength test results, the peel strength of the modified saturated polyester is increased from 1.56 KN/m to 2.55 to 3.03 KN/m, and the hot melt adhesive is adhered. The quality of the joint is improved, the adhesion of the layer in the transfer film to the surface of the object to be decorated is improved, and the quality of the decoration is optimized.

3, hot melt adhesive material adaptability test

Test method: Bonding hot melt adhesive to different materials, including PET plastic, ABS plastic, PC plastic, glass, aluminum, copper. The test was then carried out in accordance with the 180° peel strength test standard ISO 8510-2-2006. The results are shown in Table 3.

Table 3 Hot melt adhesive material adaptability test results

强度(KN/m)Strength (KN/m)	PET塑料PET plastic	ABS塑料ABS plastic	PC塑料PC plastic	玻璃片Glass piece	铝片Aluminum sheet	铜片Copper sheet
对比例Comparative example	2.012.01	1.731.73	1.651.65	1.221.22	1.561.56	1.021.02
实施例1Example 1	2.682.68	1.891.89	2.742.74	1.761.76	2.552.55	2.282.28
实施例2Example 2	2.902.90	2.342.34	2.902.90	1.981.98	3.033.03	2.342.34
实施例3Example 3	2.852.85	2.672.67	2.342.34	2.312.31	2.862.86	2.512.51
实施例4Example 4	2.792.79	2.562.56	2.122.12	2.242.24	2.732.73	2.452.45

The comparative example 0 is unmodified saturated polyester. One of the requirements of OMD transfer technology for hot melt adhesive is 180° peel strength greater than 2.0KN/m. It can be seen from the data in the table that unmodified saturated polyester Only the peel strength to PET was greater than 2.0 KN/m, and sample examples 1-4 increased the peel strength of the material to the standard. For example, the peel strength of PET, PC, aluminum, and copper in Example 1 reached the standard. Therefore, the modified polyester has increased the adaptability of the material, expanding the decorative range of the OMD technology.

4. Acid and alkali resistance and weather resistance test of hot melt adhesive

Test method: The hot-melt adhesive is bonded to the aluminum sheet to prepare the bonded test piece, and the bonded test piece is separately placed in the outdoor, artificial sweat, hydrochloric acid solution (0.1 mol/L), sodium hydroxide solution (0.1 mol/L). In the middle, the peel strength was tested on the first day, the third day, and the seventh day, respectively. The test results are shown in Table 4.

Table 4 Hot melt adhesive acid and alkali resistance, weather resistance test results

It can be seen from the table that the comparative example has a large loss of peel strength after soaking in the test liquid, because the saturated polyester has a large number of ester bonds in its main chain, and the ester bond is easily hydrolyzed and broken in an acid-base environment and ultraviolet light. , causing the phenomenon that the polyester hot melt adhesive is poor in acid and alkali resistance. The polyester modified as described above exhibits good resistance in the test liquid. For example, the peel strengths of the sample of Example 1 after immersion in HCl for one day, three days, and seven days are respectively 2.43, 2.23, and 1.67 KN/m, and the peeling is performed. The strength loss was 0.76 KN/m, while the sample comparative loss lost 1.23 KN/m after seven days. This is due to the modified interpenetrating network structure formed by chloroacetic resin and saturated polyester. The chloroacetic resin has good acid and alkali resistance, and its molecular weight has a wrap-around effect on the ester bond. It has a protective effect, thus improving its acid and alkali resistance and weather resistance. The hot-melt adhesive has improved acid and alkali resistance and weather resistance, which optimizes the weather resistance of the decorative coating and prolongs its service life.

The above content is only a preferred embodiment of the present invention, and those skilled in the art will have a change in the specific embodiment and application scope according to the idea of the present invention. The content of the present specification should not be construed as the present invention. The scope of the invention is therefore defined by the scope of the claims.

Claims

A hot melt adhesive for use in an off-film transfer technique, comprising: a mass fraction of:

Wherein, the basic resin is synthesized by a modified chloroacetate resin and a saturated polyester under the action of a diisocyanate.
The hot melt adhesive according to claim 1, wherein the substance for synthesizing the base resin is diisocyanate, modified chloroacetate resin and saturated polyester, and the mass fraction ratio of the three is 1 to 2:2 to 3 : 5 to 7.
The hot melt adhesive according to claim 2, wherein the modified chloroacetate resin is obtained by reacting N-2-aminoethyl-2-hydroxypropionamide with a ternary chloroacetate resin;

The N-2-aminoethyl-2-hydroxypropionamide is composed of the following mass fraction ratio substances.

Lactic acid 45 to 50%;

Ethylenediamine 50 to 55%.
The hot melt adhesive according to claim 2, wherein the diisocyanate is toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diene. One or more of isocyanate and lysine diisocyanate.
The base resin of the hot melt adhesive according to claim 3, wherein the ternary chloroacetate resin is a terpolymer of vinyl acetate, vinyl chloride and maleic anhydride; the mass fraction of the three is

Vinyl acetate 13-15%;

Vinyl chloride 81～84%

Maleic anhydride 1 to 6%.
The base resin of a hot melt adhesive according to claim 3, wherein the saturated polyester is a high molecular polymer obtained by dehydration condensation reaction of a dihydric alcohol and a dibasic acid, and the molecular weight of the saturated polyester is 10,000. ～50000; the diol is one or more of ethylene glycol, propylene glycol and butylene glycol; the dibasic acid is one of terephthalic acid, isophthalic acid and phthalic acid Or a variety.
A method of preparing a hot melt adhesive according to claim 1, comprising:

Step (1), placing the basic resin and the organic solvent in a container with a stirring device, controlling the temperature at 30 to 35 ° C, stirring and dissolving;

Step (2), sequentially adding a tackifier, a viscosity modifier and an antioxidant, heating to 60-80 ° C, sealing the container, stirring for 30 to 40 minutes;

Step (3), stop heating, keep warm for 30 minutes, let it cool naturally to room temperature.
A method of preparing a hot melt adhesive according to claim 7, wherein the method for preparing the base resin comprises:

Step A, the saturated polyester is dissolved in an organic solvent, wherein the mass fraction of the saturated polyester is 40 to 50%, and the mass fraction of the organic solvent is 50 to 60%;

Step B, adding modified chloroacetate resin and diisocyanate, maintaining the reaction temperature in a four-necked bottle at 60-80 ° C, and reacting for 2 hours.
The method for preparing a hot melt adhesive according to claim 8, wherein the method for preparing the modified chloroacetate resin comprises:

Step a, weigh the appropriate amount of lactic acid and ethylenediamine in a reaction vessel, and slowly react for 30 minutes at -5 ° C. When the reactants are converted into a light yellow oily liquid, the reaction is placed in an oven at 60 ° C to dry. , obtaining N-2-aminoethyl-2-hydroxypropionamide;

Step b, the ternary chloroacetate resin is dissolved in an organic solvent, wherein the mass fraction of the ternary chloroacetate resin is 20-30%, and the mass fraction of the organic solvent is 70-80%;

Step c, adding N-aminoethyl-2-hydroxypropionamide corresponding to 5% to 8% by mass of the ternary chloroacetate resin in the solution of step b, adding a catalytic amount, and reacting for 1 hour in a four-necked bottle The reaction temperature is 105 to 120 ° C, and the reactant is taken out and dried in an oven to remove the organic solvent for use.
A method of producing a hot melt adhesive according to claim 9, wherein said catalyst is from 1 to 3% of sodium hypophosphite.