CN111363218A

CN111363218A - Anti-sticking smooth master batch for CPE high-transparency film and preparation process thereof

Info

Publication number: CN111363218A
Application number: CN201811596974.5A
Authority: CN
Inventors: 刘小珊; 周慕纯; 张冬梅; 杨静平
Original assignee: Shantou Best Science And Technology Co ltd
Current assignee: Shantou Best Science And Technology Co ltd
Priority date: 2018-12-26
Filing date: 2018-12-26
Publication date: 2020-07-03

Abstract

The invention relates to an anti-sticking smooth master batch for a CPE high-transparency film, which is mainly used for the CPE film. The invention designs the anti-sticking smooth master batch for the CPE high-transparency film, which has the advantages of high effective content, good optical property, low haze, high transparency, good anti-sticking property and low friction coefficient, by adopting a composite formula design. The technology belongs to the field of functional polymer materials.

Description

Anti-sticking smooth master batch for CPE high-transparency film and preparation process thereof

Technical Field

The invention relates to the field of functional high polymer materials, in particular to an anti-sticking smooth master batch for a CPE high-transparency film and a preparation process thereof.

Background

With the increasing market demand at home and abroad, new materials, new processes, new technologies and new products of plastic packaging are emerging continuously. The casting film products and the used materials are continuously updated, the brand is created, the product quality and the grade are improved, the international advanced level is strived to be surpassed, meanwhile, in order to avoid the vicious competition of product homogenization and price fighting, the adjustment of the product structure is emphasized, the technical content of the existing products is improved as soon as possible, and the casting film products are positively developed in the directions of high performance and multiple functions, new raw materials, new technologies, application field widening, harmonious development of plastic packaging and environmental protection and the like.

Plastic films can be classified into stretched films, blown films and cast films (casting films), which account for 20 to 30% of the total world's film consumption, depending on the production method, and show a continuously increasing situation in the world's packaging material market. Specifically, the cast film is formed by casting a melt onto a smooth cooling roll through a head to rapidly cool the melt. After thickness measurement, traction, corona treatment and flattening, cutting off the corner with thicker edge, and unfolding and rolling the film roll again. As can be seen from the process flow, the film is not stretched during the production process and is a non-oriented flat extruded film. Therefore, the method has the characteristics of high production speed, high yield, good film transparency, glossiness and thickness uniformity, excellent performance balance and the like. Meanwhile, because the film is a flat extrusion film, the subsequent processes such as printing, compounding and the like are very convenient, and the film has wide application in the packaging of textiles, flowers, foods and daily necessities.

The growth of the cast film market in China is very strong, the growth speed of high-grade products is obviously higher than that of common cast film products in terms of product structure, and the product structure tends to be reasonable. The development of the domestic cast film industry is rapid in recent two years, so that not only are CPE cast film products greatly increased, but also imported equipment is slowed down and domestic cast film equipment is greatly developed under the national macro regulation and control policy. In order to meet the requirements of domestic and foreign markets, creating name cards, improving product grades, developing new products and occupying the market become the mainstream of the development of the cast film industry.

The Cast Polyethylene (CPE) film has the characteristics of excellent stretch resistance, transparency, flexibility, safety, no toxicity and the like, is an important component in three large packaging materials, and is widely applied to various packages of sanitation, medical treatment, food, electronics and the like. Compared with the foreign cast film industry, the cast film production in China starts late, about 20 th century 80 th, cast film production equipment, raw materials, master batches and the like are introduced, and research and development in all aspects are weak. The functional master batch special for casting PE film completely depends on the inlet at first, and then some low-end functional master batches are slowly pushed out and can only be used for producing part of common films. The whole domestic master batch industry is seen, a large amount of low-quality and low-price master batches produced by small and micro enterprises are circulated in the market, the innovation consciousness and the innovation capability are not enough, and the development prospect is great. With the adjustment of the product structure in the film industry and the demand of high-performance and multifunctional films in the market, the film master batch industry is not updated or innovated and is bound to be in a situation of low profit, marginalization and difficulty in survival.

The CPE high-permeability film is an important product in CPE films, is mainly applied to self-standing bags, food packaging composite films, bread bags, sanitary product outer packages, garment bags and the like, has transparent texture, and endows the commodities with observability and high-grade feeling. In general, in order to meet the requirements of automatic and high-speed production in the production and use processes of CPE, a release agent is often required to be added to prevent the sticking problem of the film, and a slip agent is added to reduce the friction coefficient of the film. However, due to the structural characteristics of PE itself and the fact that only ordinary release slip master batches are available on the market, it is difficult for CPE to achieve a low haze, high gloss high transmission film. First, the film has a high haze because Polyethylene (PE) itself is easily crystallized. On the other hand, the PE chain segment is very soft and has low glass transition temperature, so that the CPE film is soft and has insufficient rigidity, and when the CPE film is rolled together, molecular chains are very easy to wind under the action of pressure, so that the CPE film is bonded. Therefore, an anti-sticking smooth master batch must be added to help the opening of the film, but in the current market, the CPE anti-sticking smooth master batch basically uses calcium carbonate with large particle size and wide distribution as an anti-sticking agent, so that the opening effect is not good, and the calcium carbonate with large particle size can bring very large haze to the film. Therefore, if a CPE high-permeability film is prepared, the development of a special high-quality anti-sticking smooth master batch for the high-permeability film is one of the keys.

Disclosure of Invention

The invention aims to design a special high-transparency anti-sticking smooth master batch for cast polyethylene, which has good optical performance, high light transmittance, high gloss and low haze under the condition of meeting the normal production and use of a CPE film.

In order to achieve the purpose, the following scheme is adopted:

an anti-sticking smooth master batch for a CPE high-transparency film comprises the following components in parts by weight:

polyethylene resin 80-87

Anti-caking agent 4-6

8-15 parts of a slipping agent;

the anti-bonding agent is spherical glass beads or spherical silicon dioxide; the slipping agent is compounded from erucamide and EBS. EBS, fully known as ethylene bis stearamide.

Antiblocking agents and slip agents, also commonly referred to as openers in the cast film industry. Actually, the action principle and the purpose of the anti-caking agent and the slipping agent are different, and when the mixture ratio is proper, the anti-caking agent and the slipping agent have a synergistic effect. When multiple films are stacked together, they tend to stick together, causing problems in the winding, slitting and packaging, transportation, etc. steps during the film production process, and during the use, and thus, it is necessary to add a certain amount of antiblocking additive to the film surface layer. Meanwhile, in order to meet the requirements of high-speed and automatic production of the film, the film is required to have good automatic feeding performance, and the film is required to have excellent lubricity with a metal mold and the film, that is, the film is required to have a small friction coefficient.

As shown in fig. 1, an anti-adhesive agent is added on the surface of the film, one part of anti-adhesive particles are embedded in the surface layer of the film, and the other part of anti-adhesive particles are exposed in the air, so that the roughness of the surface of the film is increased; these "protrusions" form an air layer when the films are in contact with each other, thereby preventing the films from sticking together. The principle of the effect of the slipping agent is different, as shown in fig. 2, the slipping agent is added on the surface layer of the CPE film, and small molecules of the slipping agent are not completely compatible with the resin matrix, so that the small molecules can slowly migrate to the surface of the CPE film along with the migration of time, and a lubricating layer is formed on the surface of the CPE film. The popular analogy is that the anti-sticking agent particles can be regarded as cobblestones embedded in the film to play a role in isolating and preventing the adhesion of the film, and the slipping agent can be regarded as water or oil between the films to play a role in lubricating.

As can be seen from the optical principle, when light passes through the interface between two different dielectric layers, optical phenomena such as refraction and reflection occur due to different physical properties or refractive indexes (refractive indexes). Therefore, when the anti-sticking particles are added to the surface layer of the film, light transmission through the film may be emitted, diffusely reflected, scattered, etc. due to the refractive index difference of the dielectric layer to cause light loss, thereby affecting the light transmittance and haze of the film. The refractive index of the glass microspheres is 1.53, the refractive index of the silicon dioxide is 1.50, the refractive index of the glass microspheres is close to that of PE (the refractive index is 1.51), and if the glass microspheres are distributed and dispersed reasonably, the influence on the optical performance of the film is small. In addition, the high sphericity fraction of the particle type can reduce the friction coefficient of the film to a certain extent, and endow the film with smooth hand feeling.

The particle size and size distribution of the anti-blocking agent particles also have a large influence on film blocking and optical properties. For example, when the particles are too small, the film should theoretically have a high light transmittance, a small proportion of effective "protruding structures" formed on the surface of the film by the small particles is small, and the same amount of small particles is added, the loss ratio of light scattering is high, which may result in poor anti-adhesion effect and low light transmittance, while the anti-adhesion agent with too small particle size is more difficult to disperse. Too large particles may form visible white spots on the film, which may also result in higher screen pressure during film production. In conclusion, the anti-bonding particles with narrow distribution and the central particle size of 6-8um are preliminarily selected, and the particle size of the anti-bonding particles is well matched with the CPE surface layer.

As also mentioned above, CPE high permeability films are commonly used in stand-up bags, food hygiene packaging bags, garment bags, composite films, tissue films, and the like. The film generally requires that the slipping agent has the performance of high efficiency and no precipitation, does not influence the compounding and heat sealing of the film, and conforms to the relevant regulations of food safety contact materials. The erucamide and the EBS have high temperature resistance, and are beneficial to the processing performances of later heat sealing and the like.

Preferably, the composition comprises the following components in parts by weight:

preferably, the spherical silica has a central particle diameter of 6 to 8 um. The central particle size is 6 μm, and the particle size distribution is narrow. The silica with high sphericity ratio can reduce the friction coefficient of the surface of the film. And the refractive index of the silicon dioxide is 1.50, is very close to that of CPE (chlorinated polyethylene) 1.51, and has low haze and high transparency.

A process for preparing the anti-sticking smooth master batch for the CPE high-transparency film comprises the following steps:

A. predrying polyethylene resin, anti-sticking agent and slipping agent;

B. pre-melting the compounded slipping agent, adding the anti-sticking agent in proportion, and uniformly mixing;

C. proportionally adding polyethylene resin through a main feeding port of a double-screw extruder, fully heating and melting, adding an anti-adhesion agent and a slipping agent which are uniformly mixed in proportion through a side feeding port of the double-screw extruder, and extruding and granulating;

D. cooling and pelletizing;

E. and (5) drying a finished product.

The anti-caking agent is usually powder and has the characteristics of light weight, easy moisture absorption and dust raising, while the slipping agent is organic micromolecule, the compatibility of the organic micromolecule and the resin matrix is general, and the processing property of the organic micromolecule and the resin matrix is greatly different from that of polyethylene resin, so that the film is processed by using the functional master batch with high difficulty, mainly because the content of the functional master batch is difficult to control and disperse.

The invention solves the problem of additive dispersion through pre-dispersion and post-processing dispersion. The anti-sticking particles are light in weight, and the melting point of the slipping agent is low, so that preliminary setting is carried out, single or compound slipping agent is pre-melted, and the anti-sticking agent is added in proportion and blended with the slipping agent. The content is controlled by a weight loss scale with the precision degree greater than five thousandths of a whole. The whole process is controlled by adopting a numerical control network pressure, the dispersibility of the additive in the melt is monitored, and if the anti-sticking agent is agglomerated or is difficult to disperse in the master batch, the network pressure or the anti-sticking agent is suddenly increased, and the equipment prompts abnormal alarm. Meanwhile, the ash content is monitored every half hour, the content of the anti-caking agent in the master batch is detected, and the dispersion of the additive in the master batch is monitored from the aspects of processing and detection.

The invention has the following advantages:

(1) the anti-sticking and slipping master batch for the CPE film, which has good dispersibility and the effective content of up to 20 percent, is prepared by an extrusion method by adopting a high-transparency anti-sticking agent and slipping agent compounding formula, so that the production procedures of downstream manufacturers are saved, and the transportation cost and the use cost of customers are reduced.

(2) Good anti-sticking performance and low friction coefficient. Glass beads or spherical silicon dioxide (the central particle size is 6-8um) with narrow particle size distribution and the particle size close to the surface layer of the CPE film are selected as the anti-sticking agent, and particles which are sufficiently prominent can ensure that the film has good anti-sticking effect and certain smoothness.

(3) Good optical property, low haze and high transparency. The anti-sticking smooth master batch is reasonably added, and the prepared film has low haze (haze is less than 5%), high glossiness (glossiness is greater than 85%) and continuous smooth effect (friction coefficient is less than 0.3).

Drawings

FIG. 1 is a schematic illustration of the anti-sticking principle;

figure 2 is a schematic illustration of slip agent migration.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to specific embodiments.

Example 1

the central particle diameter of the spherical silica is 6-8 um.

Is prepared by the following steps:

A. predrying polyethylene resin, anti-sticking agent and slipping agent;

D. cooling and pelletizing;

E. and (5) drying a finished product.

Example 2

the central particle diameter of the spherical silica is 6-8 um.

Is prepared by the following steps:

A. predrying polyethylene resin, anti-sticking agent and slipping agent;

D. cooling and pelletizing;

E. and (5) drying a finished product.

Example 3

the central particle diameter of the spherical silica is 6-8 um.

Is prepared by the following steps:

A. predrying polyethylene resin, anti-sticking agent and slipping agent;

D. cooling and pelletizing;

E. and (5) drying a finished product.

Example 4

is prepared by the following steps:

A. predrying polyethylene resin, anti-sticking agent and slipping agent;

D. cooling and pelletizing;

E. and (5) drying a finished product.

Example 5

the central particle diameter of the spherical silica is 6-8 um.

Is prepared by the following steps:

A. predrying polyethylene resin, anti-sticking agent and slipping agent;

D. cooling and pelletizing;

E. and (5) drying a finished product.

Example 6

is prepared by the following steps:

A. predrying polyethylene resin, anti-sticking agent and slipping agent;

D. cooling and pelletizing;

E. and (5) drying a finished product.

Example 7

The anti-sticking smooth master batch for the CPE high-transparency film prepared in the examples 1-6 is added to the surface layer of the film to prepare the film, the addition amount is 2%, and the friction coefficient is tested, wherein the results are shown in the following table:

from the table, it can be known that the more the addition amount of the slip agent is, the better the slip agent is, when a certain critical value is reached, the friction coefficient is increased, and the formula is tested for many times to obtain the compound erucamide: EBS is 8%: the friction coefficient at 5% is the lowest, i.e., the release slip concentrate for CPE high transmission films prepared in example 5 is most desirable.

Example 8

Taking the anti-sticking smooth master batch for the CPE high-transparency film prepared in the embodiment 5 of the invention as an example, 1%, 1.5% and 2% are added on the surface layer of the film to prepare the film, and the film is taken as 3 experimental groups; meanwhile, an anti-sticking smooth master batch (the master batch mainly comprises calcium carbonate, talcum powder, oleamide, erucamide and the like) for CPE films purchased in the market is added with 1%, 2% and 4% of the master batch on the surface layer of the film to prepare the film, and the film is used as a 3-group comparison group; set 1 blank control group. The above 7 groups of products were compared for performance testing as shown in the following table:

note: adhesion force corona face is excellent at less than or equal to 40g against corona face according to ASTM D3354; the non-corona surface is better than or equal to 10 g; the non-corona surface is better than or equal to 15 g; the surface is shown as corona side to corona side adhesion. (the effective content of the product is 18 percent, the effective content of the product in the market is 10 percent, and the content algorithm in the surface layer is the additive amount of the master batch effective content.)

As can be seen from the table above, the product of the invention has less usage amount, but has better friction coefficient, adhesive force, haze, clarity and yield.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. An anti-sticking smooth master batch for a CPE high-transparency film is characterized by comprising the following components in parts by weight:

polyethylene resin 80-87

Anti-caking agent 4-6

8-15 parts of a slipping agent;

the anti-bonding agent is spherical glass beads or spherical silicon dioxide; the slipping agent is compounded by erucamide and EBS.

2. The anti-sticking smooth master batch for the CPE high-transparency film according to claim 1, which is characterized by comprising the following components in parts by weight:

3. the anti-sticking smooth master batch for the CPE high-transparency film according to claim 2, which is characterized by comprising the following components in parts by weight:

4. the anti-sticking smooth masterbatch for the CPE high permeable film according to claim 3, wherein the spherical silica has a center particle size of 6 to 8 um.

5. A process for preparing the anti-sticking smooth master batch for the CPE high-transparency film according to the claims 1 to 4, which is characterized by comprising the following steps:

A. predrying the polyethylene resin, the anti-sticking agent and the slipping agent;

C. proportionally adding the polyethylene resin through a main feeding port of a double-screw extruder, fully heating and melting, adding the anti-sticking agent and the slipping agent which are uniformly mixed in proportion through a side feeding port of the double-screw extruder, and extruding and granulating;

D. cooling and pelletizing;

E. and (5) drying a finished product.