CN118813034A - A TPU film firmly bonded with acrylic pressure-sensitive adhesive and a preparation method thereof - Google Patents

Abstract

The present invention relates to a TPU film that is firmly bonded to an acrylic pressure-sensitive adhesive and a preparation method thereof, and belongs to the technical field of TPU films. The present invention promotes the combination between TPU and acrylic pressure-sensitive adhesive by adding PMMA, thereby improving the bonding effect between the two; in the present invention, the added flame-retardant masterbatch is modified, and _a ZnO- _Al2O3 composite with uniform particle size is obtained by controlling the roasting temperature, and light calcium carbonate, nano-silicon dioxide and PPS are mixed under a nitrogen environment, and the addition of the modified flame-retardant masterbatch further improves the performance of TPU; the present invention uses a direct casting method when preparing the TPU film, and does not perform embossing treatment at the three-roller position, so that the obtained film has the advantages of more uniform quality, higher transparency and glossiness, better mechanical properties and higher production efficiency.

Description

A TPU film firmly bonded with acrylic pressure-sensitive adhesive and a preparation method thereof

Technical Field

The invention belongs to the technical field of TPU films and relates to a TPU film firmly bonded with an acrylic pressure-sensitive adhesive and a preparation method thereof.

Background Art

TPU material is a new type of polymer elastomer material favored by all walks of life due to its good comprehensive performance. Among them, TPU film has been increasingly used in clothing, shoes, bags, medical, automobile, military, electronics and other fields; especially with the explosive growth of new energy vehicles, its interior seat ventilation system has become a regular configuration; the demand for TPU ventilation bags has increased rapidly. However, the poor bonding ability of TPU material and acrylic pressure-sensitive adhesive has caused trouble for its subsequent finished product processing.

Therefore, a TPU film that is well bonded with acrylic pressure-sensitive adhesive has become an urgent problem to be solved in the TPU film industry.

Summary of the invention

The purpose of the present invention is to provide a TPU film which can be firmly bonded with an acrylic pressure-sensitive adhesive and a preparation method thereof, and the film has the characteristics of being flame retardant and being well bonded with the pressure-sensitive adhesive.

The purpose of the present invention can be achieved through the following technical solutions:

A TPU film that is firmly bonded to an acrylic pressure-sensitive adhesive, wherein the TPU film formula is, by weight, 100 parts of thermoplastic polyurethane rubber TPU, 10 parts of polymethyl methacrylate PMMA, 5 parts of modified flame retardant masterbatch, 0.5 parts of dispersant, and 0.5 parts of coupling agent.

Among them, the preparation method of the modified flame retardant masterbatch is as follows:

S1: zinc nitrate and aluminum nitrate were mixed in a mass ratio of 1:1, put into a ball mill and ground at a grinding speed of 300 r/min for 1 h to obtain a mixture A;

S2: Raise the temperature of mixture A from room temperature to 500°C at a rate of 3°C/min, calcine at 500°C for 4 hours, and cool to room temperature to obtain a ZnO-Al ₂ O ₃ composite;

S3: ZnO-Al ₂ O ₃ , light calcium carbonate and nano-silicon dioxide were mixed in a mass ratio of 1:1:0.8, and ground in a ball mill at a speed of 300 r/min for 0.5 h to obtain a mixture B;

S4: Mix the mixture B and polyphenylene sulfide resin PPS in a mass ratio of 1:3 and put them into a mixer, heat them to 285° C. under a nitrogen atmosphere to make the mixture semi-molten, add 1 wt % polyethylene glycol-2000, and stir at a speed of 60 r/min for 2 h to obtain a mixture C;

S5: Under a nitrogen atmosphere, the mixture C is passed through a die, cooled and shaped, and pelletized to obtain the modified flame retardant masterbatch.

Furthermore, the plastic polyurethane rubber TPU is a polyether TPU with a hardness of 85-90 Shore A.

Furthermore, the dispersant is ethylene bisstearamide.

Furthermore, the coupling agent is one of vinylmethyldimethoxysilane and vinyltriethoxysilane.

A method for preparing a TPU film that is firmly bonded to an acrylic pressure-sensitive adhesive. The specific process of the method for preparing the TPU film is as follows:

S51: Put TPU into a ball mill according to the formula ratio and grind it at a speed of 400 r/min for 1 hour, then add PMMA, modified flame retardant masterbatch, dispersant and coupling agent, and continue grinding for 1 hour to obtain a mixture D;

S52: Mixture D is stirred in a mixer at a speed of 40 r/min, heated to 100° C., stirred at 100° C. for 0.5 h, passed through a die, cooled and pelletized to obtain a modified TPU material;

S53: placing the modified TPU material into a dryer and drying it at a temperature of 80 to 90° C. for 3 to 4 hours;

S54: casting the dried modified TPU material into a TPU film through an extruder by a direct casting process, and no embossing treatment is performed at the three rollers;

S55: After extrusion casting, the film is allowed to stand for 12 hours, cooled and rolled up, and the finished product is packaged to obtain the TPU film.

Furthermore, the grinding temperature in S51 is 25°C.

Furthermore, the particle size of the mixture D obtained by grinding in S51 is 200 mesh.

Furthermore, the modified TPU material in S53 is dried until the moisture content is less than 0.03%.

Furthermore, the cooling temperature in S55 is 25°C.

The technical problem solved by the present invention is to provide a method for preparing a TPU film that is well bonded to an acrylic pressure-sensitive adhesive. The TPU film prepared by the present invention has the advantages of flame retardancy, high adhesive tape peeling force, good bonding to acrylic acid and pressure-sensitive adhesive, simple processing technology, etc., and meets the needs of the automotive seat ventilation system industry.

The molecular chain of polymethyl methacrylate (PMMA) contains a large number of polar groups, which can interact with the polar groups in TPU and acrylic pressure-sensitive adhesive to form chemical bonds or physical adsorption, thereby enhancing the bonding force between them. In addition, the molecular chain of PMMA also has a certain degree of flexibility, which can alleviate the stress concentration between TPU film and acrylic pressure-sensitive adhesive to a certain extent, and improve the uniformity and stability of the bonding;

In addition, PMMA has high transparency, which means that after adding PMMA to TPU film and acrylic pressure-sensitive adhesive, the transparency of the product can still be maintained or improved; PMMA has good weather resistance, and TPU film and acrylic pressure-sensitive adhesive containing PMMA can maintain good performance after long-term use, and are not prone to aging, discoloration and other problems; the addition of PMMA can also improve the compatibility of TPU film and acrylic pressure-sensitive adhesive. Since PMMA has good compatibility with both TPU and acrylic pressure-sensitive adhesive, adding PMMA can promote the combination between them and improve the bonding effect.

The present invention also modifies the added flame retardant masterbatch to further improve the performance of TPU. First, zinc nitrate and aluminum nitrate are calcined at 500°C. The calcination at this temperature can ensure that zinc nitrate and aluminum nitrate are fully decomposed to form zinc oxide and aluminum oxide crystals, and the calcination at this temperature helps to obtain a ZnO- _{Al2O3 composite} with a stable structure and high crystallinity. The calcination temperature of 500°C will not cause excessive growth of particles, so that a smaller particle size and a larger specific surface area can be maintained, and the particles can be more easily dispersed when mixed with other materials, thereby improving the performance stability of the modified flame retardant masterbatch. More active sites will be formed on the surface of the ZnO- _{Al2O3 composite} calcined at 500°C.

Calcination at 500℃ will cause some substances on the surface _of ZnO and _Al2O3 to migrate and rearrange. ZnO substances will migrate to the surface of _Al2O3 . This surface reconstruction process will enrich Zn elements on the surface of the _composite , forming more abundant Zn-O-Al interface sites. The interaction between Zn elements and oxygen atoms _on the surface of _Al2O3 can increase the adsorption performance and active sites on the surface of ZnO- _{Al2O3 composites} , which are conducive to better combination with light calcium carbonate and nano-silicon _dioxide . The enrichment of Zn elements also changes the electronic structure of the surface of ZnO- _Al2O3 composites. The change in electronic structure makes it easier for the surface of the composite to provide electrons, so that the composite and PPS materials can be better combined through electron exchange.

The ZnO-Al ₂ O ₃ compound itself has certain flame retardant properties. The addition of light calcium carbonate and nano-silicon dioxide can further improve the flame retardant effect of the material. The nano-scale size of nano-silicon dioxide gives it a large specific surface area and activity, which can more effectively react with free radicals in the flame, thereby interrupting the combustion chain reaction. As a polymer material, PPS has excellent heat resistance and chemical stability, and is non-toxic and odorless, meeting environmental protection requirements. Mixing in a nitrogen environment avoids the influence of oxygen on material properties, prevents the material from being oxidized to produce impurities, ensures the purity of the modified flame retardant masterbatch, and also reduces the emission of harmful gases. The modified flame retardant masterbatch prepared by combining the ZnO-Al ₂ O ₃ compound with polymer materials such as PPS can also improve the strength and hardness of the TPU film.

The present invention uses a direct casting method when preparing the TPU film. The directly cast TPU film has a more uniform thickness and higher quality stability, and is not embossed at the three rollers, so that the problem of uneven local pressure caused by embossing, which leads to uneven thickness of the film, can be avoided; the surface of the TPU film without embossing is smoother, so it has better transparency and glossiness, which makes the film more visually beautiful; the directly cast TPU film does not undergo additional embossing treatment, so its mechanical properties are more stable, which makes the film more durable in operations such as stretching and bending; the production process of the directly cast TPU film is simpler, so it has higher production efficiency.

Beneficial effects of the present invention:

The invention promotes the combination between TPU and acrylic pressure-sensitive adhesive by adding PMMA, _thereby improving the lamination effect between the two. In the invention, the added flame retardant masterbatch is modified, and a ZnO- _Al2O3 composite with uniform particle size is obtained by controlling the roasting temperature, and light calcium carbonate, nano silicon dioxide and PPS are mixed under a nitrogen environment, and the addition of the modified flame retardant masterbatch further improves the performance of TPU. The invention uses a direct casting method when preparing the TPU film, and does not perform embossing treatment at the three-roller position, so that the prepared film has the advantages of more uniform quality, higher transparency and glossiness, better mechanical properties and higher production efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

Figure 1. Production process of TPU film.

DETAILED DESCRIPTION

In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

Example 1

The formula of TPU film is 100 parts of thermoplastic polyurethane rubber TPU, 10 parts of polymethyl methacrylate PMMA, 5 parts of modified flame retardant masterbatch, 0.5 parts of ethylene bis stearamide, and 0.5 parts of vinyl methyl dimethoxy silane.

Among them, the preparation method of the modified flame retardant masterbatch is as follows:

S1: zinc nitrate and aluminum nitrate were mixed in a mass ratio of 1:1, put into a ball mill and ground at a grinding speed of 300 r/min for 1 h to obtain a mixture A;

S2: Raise the temperature of mixture A from room temperature to 500°C at a rate of 3°C/min, calcine at 500°C for 4 hours, and cool to room temperature to obtain a ZnO-Al ₂ O ₃ composite;

S3: ZnO-Al ₂ O ₃ , light calcium carbonate and nano-silicon dioxide were mixed in a mass ratio of 1:1:0.8, and ground in a ball mill at a speed of 300 r/min for 0.5 h to obtain a mixture B;

S4: Mix the mixture B and polyphenylene sulfide resin PPS in a mass ratio of 1:3 and put them into a mixer, heat them to 285° C. under a nitrogen atmosphere to make the mixture semi-molten, add 1 wt % polyethylene glycol-2000, and stir at a speed of 60 r/min for 2 h to obtain a mixture C;

S5: Under a nitrogen atmosphere, the mixture C is passed through a die, cooled and shaped, and pelletized to obtain the modified flame retardant masterbatch;

The specific process of the preparation method of the TPU film is as follows:

S51: Put TPU into a ball mill for grinding according to the formula ratio, the grinding temperature is 25°C, the grinding is carried out at a speed of 400r/min, the grinding time is 1h, and then PMMA, modified flame retardant masterbatch, dispersant and coupling agent are added, and the grinding is continued for 1h to obtain a mixture D, and the particle size of the mixture D is 200 mesh;

S52: Mixture D is stirred in a mixer at a speed of 40 r/min, heated to 100° C., stirred at 100° C. for 0.5 h, passed through a die, cooled and pelletized to obtain a modified TPU material;

S53: placing the modified TPU material into a dryer and drying it at a temperature of 80 to 90° C. for 3 to 4 hours until the water content of the modified TPU material is less than 0.03%;

S54: casting the dried modified TPU material into a TPU film through an extruder by a direct casting process, and no embossing treatment is performed at the three rollers;

S55: After extrusion casting, the film is allowed to stand at 25° C. for 12 hours, cooled and rolled up, and the finished product is packaged to obtain the TPU film.

Comparative Example 1

In this comparative example, polymethyl methacrylate (PMMA) was not added, and the other steps were consistent with those in Example 1.

Comparative Example 2

In this comparative example, polymethyl methacrylate PMMA is replaced by soft acrylic 60A, and the other steps are the same as those in Example 1.

Comparative Example 3

In this comparative example, unmodified flame retardant masterbatch was used to obtain 2285AMR, and the other steps were consistent with Example 1.

The experimental data of the embodiments and comparative examples are summarized in the following table:

Test description: The test sample is conditioned at (23±2)℃, (50±10)%RH for 48 hours.

From the experimental data, we can see that polymethyl methacrylate PMMA effectively improves the tape peeling force of TPU film, while the addition of modified flame retardant masterbatch effectively improves the flame retardant properties of TPU film.

The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims (9)

1. The TPU film firmly attached to the acrylic pressure-sensitive adhesive is characterized by comprising, by weight, 100 parts of thermoplastic polyurethane rubber TPU, 10 parts of polymethyl methacrylate PMMA, 5 parts of modified flame-retardant master batch, 0.5 part of dispersing agent and 0.5 part of coupling agent,

Wherein, the preparation method of the modified flame-retardant master batch is as follows,

S1: zinc nitrate and aluminum nitrate are mixed according to the mass ratio of 1:1, mixing, putting into a ball mill, and grinding at a grinding speed of 300r/min for 1h to obtain a mixture A;

S2: heating the mixture A from room temperature to 500 ℃ at a speed of 3 ℃/min, roasting at 500 ℃ for 4 hours, and cooling to room temperature to obtain a ZnO-Al ₂O₃ compound;

S3: znO-Al ₂O₃, light calcium carbonate and nano silicon dioxide are mixed according to the mass ratio of 1:1:0.8, grinding for 0.5h in a ball mill at a speed of 300r/min to obtain a mixture B;

S4: mixing the mixture B and polyphenylene sulfide resin PPS according to a mass ratio of 1:3, mixing and placing into a stirrer, heating to 285 ℃ under nitrogen atmosphere to enable the mixture to be in a semi-molten state, adding 1wt% of polyethylene glycol-2000, and stirring for 2 hours at a rotating speed of 60r/min to obtain a mixture C;

S5: and (3) under the nitrogen atmosphere, the mixture C passes through a die, is cooled and shaped, and is pelletized, so that the modified flame-retardant master batch is obtained.

2. The TPU film of claim 1, wherein said plastic polyurethane rubber TPU is a polyether TPU having a hardness of 85-90 shore a.

3. A TPU film which is firmly adhered to the acrylic pressure sensitive adhesive according to claim 1, the dispersing agent is ethylene bis stearamide.

4. The TPU film of claim 1, wherein said coupling agent is one of vinyl methyl dimethoxy silane and vinyl triethoxy silane.

5. A preparation method of a TPU film firmly attached to an acrylic pressure-sensitive adhesive, which is realized based on the TPU film firmly attached to the acrylic pressure-sensitive adhesive according to any one of claims 1 to 4, and is characterized in that the preparation method of the TPU film comprises the following specific procedures,

S51: grinding TPU in a ball mill according to the formula proportion at a rotating speed of 400r/min for 1h, adding PMMA, modified flame-retardant master batch, a dispersing agent and a coupling agent, and continuously grinding for 1h to obtain a mixture D;

S52: stirring the mixture D in a stirrer at a rotating speed of 40r/min, heating to 100 ℃, stirring at 100 ℃ for 0.5h, passing through a die, cooling and granulating to obtain a modified TPU material;

s53: the modified TPU material is put into a dryer and is dried at the temperature of 80-90 ℃ for 3-4 hours;

S54: the dried modified TPU material is cast into a TPU film through an extruder by a direct casting process, and embossing treatment is not carried out at three rollers;

S55: and (3) after extrusion casting, standing for 12 hours, cooling, rolling, and packaging the finished product to obtain the TPU film.

6. The method for preparing TPU film firmly adhered to acrylic pressure sensitive adhesive according to claim 5, the method is characterized in that the grinding temperature in the step S51 is 25 ℃.

7. The method for preparing a TPU film firmly adhered to an acrylic pressure sensitive adhesive according to claim 5, wherein the particle size of the mixture D obtained by grinding in S51 is 200 mesh.

8. The method for preparing a TPU film firmly adhered to an acrylic pressure sensitive adhesive according to claim 5, wherein the modified TPU material in S53 is dried to a moisture content of less than 0.03%.

9. The method for preparing TPU film firmly adhered to acrylic pressure sensitive adhesive according to claim 5, the cooling temperature in S55 is 25 ℃.