阅读说明：本技术 一种pp-tpu复合薄膜及其制备方法和应用 (PP-TPU composite film and preparation method and application thereof ) 是由 蔡芳昌 黄喆 阮波 吴锦 张鑫珂 张逸杰 蒋涛 于 2020-07-23 设计创作，主要内容包括：本发明公开了一种PP-TPU复合薄膜及其制备方法和应用,所述高透明PP-TPU复合薄膜,包括以下质量份数的原料：聚丙烯树脂85-92份,TPU 5-10份,相容剂3-5份,成核剂1-3份；所述聚丙烯树脂、TPU、相容剂以及成核剂均为固体材料。本发明中,通过采用相容剂以及成核剂等,使得非极性的PP以及极性的TPU得以相容,解决了两者相容性差问题,为薄膜材料的配方,提供了新的思路。本发明中,通过上述配方制备的复合薄膜,机械性能好,能够降低雾度,提高透光率,扩大其应用范围。(The invention discloses a PP-TPU composite film and a preparation method and application thereof, and the high-transparency PP-TPU composite film comprises the following raw materials in parts by mass: 85-92 parts of polypropylene resin, 5-10 parts of TPU (thermoplastic polyurethane), 3-5 parts of compatilizer and 1-3 parts of nucleating agent; the polypropylene resin, the TPU, the compatilizer and the nucleating agent are all solid materials. In the invention, the non-polar PP and the polar TPU are compatible by adopting the compatilizer, the nucleating agent and the like, so that the problem of poor compatibility of the non-polar PP and the polar TPU is solved, and a new thought is provided for the formula of the film material. The composite film prepared by the formula has good mechanical property, can reduce haze, improve light transmittance and expand the application range of the composite film.)

1. The PP-TPU composite film is characterized by comprising the following raw materials in parts by mass:

85-92 parts of polypropylene resin; 10-5 parts of TPU; 3-5 parts of a compatilizer; 1-3 parts of a nucleating agent; the polypropylene resin, the TPU, the compatilizer and the nucleating agent are all solid materials.

2. The PP-TPU composite film as claimed in claim 1, which comprises the following raw materials in parts by mass: 92 parts of polypropylene resin; 5 parts of TPU; 5 parts of compatilizer and 1 part of nucleating agent.

3. The PP-TPU composite film of claim 1 wherein the compatibilizer is one of PP-g-ST, PP-g-MAH, or PP-g-GMA.

4. The PP-TPU composite film of claim 1 wherein the nucleating agent is a sorbitol based polypropylene clear nucleating agent.

5. A method for preparing the PP-TPU composite film according to any one of claims 1 to 4, characterized in that it comprises the following steps:

pretreatment: respectively weighing polypropylene resin, TPU, compatilizer and nucleating agent in parts by weight for drying pretreatment;

mixing raw materials: blending the pretreated TPU and PP to obtain a primary mixture, and then adding a compatilizer and a nucleating agent to obtain a mixture;

and (3) granulating: granulating the mixture in a granulating device to obtain a mixture material;

blow molding: and setting parameters for the blow molding machine according to the thickness requirement of the film to obtain the film.

6. The method for preparing a PP-TPU composite film according to claim 5, wherein in the pretreatment, the drying temperature of the pretreatment is 40-60 ℃, and the time of the pretreatment is 10-14 h.

7. Use of a PP-TPU composite film according to any of claims 1-4 in the field of packaging films.

8. The use of a PP-TPU composite film as claimed in claim 7, wherein said packaging film is an outer package for products with heat shrinkability.

9. The use of a PP-TPU composite film according to claim 7 wherein said packaging film is an outer packaging for detailed product displays.

10. The use of the PP-TPU composite film as described in claim 7, wherein the packaging film is used for packaging a product by automatic heat shrinkage under the environment of 150 ℃ and 170 ℃.

Technical Field

The invention belongs to the technical field of materials and preparation thereof, and particularly relates to a PP-TPU composite film with good light transmittance and good mechanical strength.

Background

In recent years, heat shrinkable films have been widely used in the field of packaging in human life, such as food packaging and the like. Heat shrinkable films are used for the sale and transportation of various products, the main function of which is to stabilize, cover and protect the product. The shrink film must have high puncture resistance, good shrinkage and a certain shrinkage stress. During the shrinking process, the film is not able to create holes. Currently, the kinds of heat shrinkable films mainly include PE shrink films, POF shrink films, OPS shrink films, PET shrink films, and the like.

The required characteristics of the heat shrinkable film include:

1. has high flexibility, is not easy to damage, has strong anti-explosion force, strong anti-impact performance, strong tear resistance and strong tension, and can replace box packaging.

2. The shrinkage rate is large, the bag can be tightly wrapped after thermal shrinkage, and if the PE straight-through bag is manufactured (two ends of the bag are opened). After thermal contraction, the two ends of the opening can lift objects, can bear the weight of 15KG, and is convenient to carry.

3. The transparency is good, the light transmittance reaches 80%, the product can be displayed, the product can be invisibly publicized, and meanwhile, the distribution error in the logistics link is reduced.

4. Moisture-proof, waterproof and dustproof, can achieve the packaging effect, and can also beautify and protect the product.

5. Is nontoxic, tasteless and pollution-free, and belongs to an environment-friendly packaging material.

However, the existing heat shrinkable films mainly comprise heat shrinkable films such as PE and POE, which have many problems in practical use, the cost of the single-layer heat shrinkable film PE is very high, the preparation steps are complicated, and the structures of the heat shrinkable films such as POE and POF are complicated, and the operation is complicated. Although the barrier property, moisture resistance, waterproofness and the like of the polypropylene film are superior to those of a high-density polyethylene film, the heat-sealing quality of the polypropylene film is poor, and the polypropylene film is not suitable for a heat-shrinkable film; the TPU is elastomer polyurethane which is formed by jointly reacting and polymerizing diisocyanate molecules, macromolecular polyol and low molecular polyol (chain extender), has the characteristics of high tension, high tensile force, toughness and aging resistance, and is a mature environment-friendly material. By combining the advantages of low price of polypropylene and the like and the excellent tensile property of TPU material, the blending of the two materials is considered to obtain a film.

In practice, however, the simple blending of PP and TPU has the following problems:

1. the compatibility between polypropylene resin and TPU elastomer is poor, and PP flexibility is poor.

2. Films obtained by blow molding of polypropylene resins and TPU elastomers have low clarity, including high haze and low light transmittance.

In view of the above problems, the solution of the compatibility between PP and TPU is significant to the cost performance and processability of the heat shrinkable film.

Disclosure of Invention

The invention aims to provide a PP-TPU composite film which is good in transparency, mechanical property and compatibility of polypropylene resin and TPU, solves the compatibility problem of PP-TPU, and concretely, the mechanical property comprises tensile strength, elongation at break, elastic modulus and tensile yield stress. The TPU is a blown film grade polyester TPU, and the PP is a Bazier blown film grade polypropylene.

In order to achieve the technical effects, the invention is realized by the following technical means:

the PP-TPU composite film comprises the following raw materials in parts by mass:

85-92 parts of polypropylene resin, 5-10 parts of TPU (thermoplastic polyurethane), 3-5 parts of compatilizer and 1-3 parts of nucleating agent;

the polypropylene resin, the TPU, the compatilizer and the nucleating agent are all solid materials.

In the technical scheme, the compatilizer, the nucleating agent and the like are adopted, so that the nonpolar PP and the polar TPU are compatible, the problem of poor compatibility of the nonpolar PP and the polar TPU is solved, and a new thought is provided for the formula of the film material.

In the technical scheme, the composite film prepared by the formula has the problem of good transparency, and can reduce haze, improve light transmittance and expand the application range of the composite film.

In the technical scheme, a pure solid material is adopted as a raw material, excessive chemical reaction is not needed through simple mixing, and the whole formula is high in safety, low in cost and good in use efficiency in the preparation process. Compared with the prior art, the composite film is prepared under the extremely high requirement environment through a series of steps such as a plurality of chemical reactions or electrical reactions, the process is simple, the raw materials are simple, the preparation method is easy to obtain, the production is more convenient, and the large-scale popularization is realized.

As a further improvement of the invention, the feed comprises the following raw materials in parts by mass: 92 parts of polypropylene resin; 5 parts of TPU; 5 parts of compatilizer and 1 part of nucleating agent.

In the embodiment, the tensile strength reaches 9.47MPa, the elongation at break reaches 470.17%, and the elongation at break is far greater than that of composite films of other formulas; while the tensile yield stress is as high as 9.45MPa, and the elastic modulus is as low as 34.27. In terms of transparency, haze was also reduced to 39.04, and light transmittance was as high as 91.22.

As a further improvement of the invention, the compatilizer is one of PP-g-ST, PP-g-MAH or PP-g-GMA.

By selecting these compatibilizers, incompatible polypropylene and TPU can be brought together to give a stable blend. The addition of chemical catalysts, reactants and reagents is reduced, and the use is safer and more convenient.

Specifically, the mechanism of action of PP-g-ST (polypropylene grafted styrene), PP-g-MAH (maleic anhydride grafted polypropylene) or PP-g-GMA (polypropylene grafted glycidyl methacrylate) is as follows: the two incompatible polymers are forced together by intermolecular bonding forces. When the two materials are incompatible, the third material can be added to make them respectively compatible.

As a further improvement of the invention, the nucleating agent is a sorbitol polypropylene transparent nucleating agent.

In the technical scheme, the sorbitol polypropylene transparent nucleating agent is used as the nucleating agent, the recommended addition amount is 0.10-0.30%, the product can meet the safety certification requirement of food packaging materials, the thermal deformation temperature of the product is improved, the molding period is shortened, and the problems of smell, whiteness and the like of the nucleating agent are solved.

The invention also discloses a preparation method of the PP-TPU composite film, which comprises the following steps:

pretreatment: respectively weighing polypropylene resin, TPU, compatilizer and nucleating agent in parts by weight for drying pretreatment;

mixing raw materials: blending the pretreated TPU and PP to obtain a primary mixture, and then adding a compatilizer and a nucleating agent to obtain a mixture;

and (3) granulating: granulating the mixture in a granulating device to obtain a mixture material;

blow molding: and setting parameters for the blow molding machine according to the thickness requirement of the film to obtain the film.

In the technical scheme, the TPU and the PP are fully mixed through the steps of pretreatment, mixing firstly, mixing secondly, granulating and the like, so that respective advantages are exerted, and a required high-transparency TPU composite film is formed conveniently.

According to the invention, the compatibility of various solids can be realized without adding a chemical reagent or chemical reaction, so that a film with mechanical properties and transparency meeting the requirements can be conveniently formed in the later period, the film is convenient to popularize and apply, the use is safer, and the production cost is greatly reduced.

As a further improvement of the invention, in the pretreatment, the drying temperature of the pretreatment is 40-60 ℃, and the time of the pretreatment is 10-14 h.

In the technical scheme, the drying aims to remove the moisture of the raw materials and improve the processing efficiency and performance of melt blending of the materials. In the technical scheme, the drying temperature is 40-60 ℃ and lower than 40 ℃, so that the drying needs longer time, and the process time is too long; and when the temperature is higher than 60 ℃, part of raw materials are easy to melt and bond, and the processing is difficult in the later period.

The invention also discloses an application of the PP-TPU composite film in the field of packaging films.

The composite film produced in the technical scheme can be used as packages of daily necessities, fragile products and other products, particularly as a film for packaging, has the characteristics of low cost, convenient production and simple process, and can realize good packaging of the products due to strong mechanical property and good light transmittance when being used for packaging.

As a further improvement of the present invention, the packaging film is an outer package of a product having heat shrinkability.

In the technical scheme, the product with the heat shrinkage performance specifically refers to a product affected by expansion with heat and contraction with cold, such as various rubber products and the like.

The invention can be used for heat-shrinkable products because of high elongation at break of the packaging film, and the packaging effect of the film cannot be influenced by the change of the size of the product when the product is subjected to expansion caused by heat and contraction caused by cold.

As a further improvement of the invention, the packaging film is an outer package for the display of detailed products.

In the technical scheme, the composite film has high transparency, so that when some products need to be displayed in detail, the effect of the invention is better compared with other films. Such as electronic products with displays, or some industrial products that need to be displayed locally, etc. For example, the outer packaging film for telephone watches and the outer packaging film for industrial intelligent instruments and meters.

As a further improvement of the invention, in the application, after the product is packaged by the packaging film, the packaging is realized by automatic heat shrinkage under the environment of 150-170 ℃.

In the technical scheme, after the product is primarily packaged, the automatic heat-shrinkable packaging can be realized through the processing steps of the heat-shrinkable packaging at the high temperature of 150-.

Drawings

FIG. 1 is a drawing showing the tensile strength test result of a PP-TPU composite film with high transparency and high mechanical strength provided by the invention;

FIG. 2 is a graph showing the elongation at break test result of a PP-TPU composite film with high transparency and high mechanical strength provided by the invention;

FIG. 3 is a drawing showing the tensile yield stress test result of a PP-TPU composite film with high transparency and high mechanical strength provided by the invention;

FIG. 4 is a graph showing the result of the elastic modulus test of a PP-TPU composite film with high transparency and high mechanical strength according to the present invention;

FIG. 5 is a graph showing the result of the transmittance test of a PP-TPU composite film with high transparency and high mechanical strength according to the present invention;

FIG. 6 is a haze test result diagram of a PP-TPU composite film with high transparency and high mechanical strength provided by the invention.

Detailed Description

The invention will be explained with reference to the drawings and the embodiments.