CN104151499A - Preparation method of printable polypropylene material - Google Patents

Abstract

The invention discloses a preparation method of a printable polypropylene material; in the method, the polypropylene material is placed in a supercritical carbon dioxide fluid containing a polar monomer and an initiator at a pressure of 7.4MPa-15MPa and a temperature of After soaking at 32°C-100°C for 6 hours to 3 days, take it out and place it under normal temperature and pressure for 1 hour-4 hours; the mass ratio of polar monomer to carbon dioxide in the supercritical carbon dioxide fluid is 1-10:100; the initiator and The mass ratio of the polar monomer is 0.5-10:100; then the treated polypropylene material is grafted. The present invention only treats the surface layer or surface of the polypropylene material, and the heat treatment temperature is much lower than the melting point of polypropylene, and the ultraviolet irradiation time is shorter. Therefore, the present invention can improve the overall performance of the polypropylene material while maintaining the excellent comprehensive performance of the polypropylene material. It improves the surface printability and the scratch resistance of the printed layer.

Description

A kind of preparation method of printable polypropylene material

technical field

The invention relates to the technical field of plastic materials or products, in particular to a method for preparing a printable polypropylene material.

Background technique

Polypropylene has low density, high mechanical strength, good chemical resistance, low price, easy molding, and strong

It can be widely used in films, sheets, plates, fabrics, non-woven fabrics, auto parts and daily necessities. However, due to its low molecular polarity, the surface energy of polypropylene materials (including isotactic polypropylene, atactic polypropylene, syndiotactic polypropylene, random copolymer polypropylene or block copolymer polypropylene) or articles is very low, and its The surface energy is generally only 28-32 dyne, it is difficult to print on the surface, and the scratch resistance of the printed layer is poor. Moreover, due to the high crystallinity of polypropylene, it is difficult to carry out surface modification on its products.

Various methods can be used to improve the surface printability of polypropylene materials or products, such as surface treatment, blending modification, and overall graft modification of materials. When the surface energy of the polypropylene material or product is higher, it has better printability and better scratch resistance of the printed layer.

Ozone treatment, corona discharge treatment, plasma treatment, ultraviolet light irradiation treatment and other direct treatment methods are often used to treat the surface of materials or products to improve the surface energy of polypropylene materials or products. However, after such surface treatment, the surface can be The printability continued to decline with the prolongation of the storage time after treatment, and the scratch resistance of the printed layer was poor.

Through modification methods, increasing the overall polarity of polypropylene materials can also improve the printability of polypropylene products. Common modification methods such as mixing polypropylene with polar materials and inoculating polar monomers on polypropylene materials branch modification. Chinese patent (application number 200580045739.3) introduces a method of blending chlorinated polypropylene and polypropylene to increase the polarity of polypropylene. This method needs to add more chlorinated polypropylene to polypropylene, which will increase the cost of materials or products, and reduce the overall performance of polypropylene materials. A common method for grafting and modifying polypropylene materials with polar monomers is the melt grafting method. The melt grafting operation is simple and the production efficiency is high, but in the melt grafting process, the side reaction of polypropylene macromolecule degradation is prone to occur and the material performance is deteriorated, although the addition of comonomers during the melt grafting process can reduce the degradation side reaction , but the comonomer may induce the crosslinking of polypropylene macromolecules, which will affect the processability of polypropylene materials and the gloss and smoothness of the surface of products.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a polypropylene material with good printability and excellent scratch resistance, which will not cause the main physical and mechanical properties of the polypropylene material or product to decrease.

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

A method for preparing a printable polypropylene material, comprising the steps of:

1): The polypropylene material is placed in supercritical carbon dioxide fluid containing polar monomers and initiators, soaked at a pressure of 7.4MPa-15MPa and a temperature of 32°C-100°C for 6 hours to 3 days, and then taken out at room temperature Placed under normal pressure for 1 hour-4 hours; the mass ratio of the polar monomer to the carbon dioxide in the supercritical carbon dioxide fluid is 1-10:100; the mass ratio of the initiator to the polar monomer is 0.5-10: 100;

The polar monomers are maleic anhydride, acrylic acid, methacrylic acid, vinyl acetate, hydroxyethyl acrylate, and hydroxyethyl methacrylate.

The initiator is dicumyl peroxide, di-tert-butyl peroxide, diisopropyl peroxydicarbonate, dibenzoyl peroxide, diphenyldodecanoyl peroxide, azobisisobutyronitrile, Azobisisoheptanonitrile, or benzophenone, 4,4'-dimethylaminobenzophenone, diethoxyacetophenone, dichloroacetophenone;

2): performing grafting treatment on the polypropylene material treated in step (1).

Preferably, the polypropylene material is isotactic polypropylene, atactic polypropylene or syndiotactic polypropylene,

In terms of mass percentage, the polypropylene material is random copolymerized polypropylene added with 1%-4% ethylene or block copolymerized polypropylene added with more than 4% ethylene.

The shape of the polypropylene material is film, sheet, plate or fiber. Alternatively, the shape of the polypropylene material is in the form of fabric or non-woven fabric.

In addition to carbon dioxide, the supercritical carbon dioxide fluid also includes a mixed system composed of acetone, chloroform, ethyl acetate, toluene, cyclohexane and carbon dioxide; the acetone, chloroform, ethyl acetate, toluene, cyclohexane and carbon dioxide The dosage accounts for 2%-20% of the mass of the supercritical carbon dioxide system.

The grafting treatment is heat treatment, or ultraviolet irradiation treatment, or combined treatment of heating and ultraviolet irradiation. The temperature of the heat treatment is 60°C-130°C, and the time is 10min-60min; the wavelength of the ultraviolet rays is 320nm-450nm, and the irradiation time of ultraviolet rays is 1min-10min.

Compared with the prior art, the present invention has the following advantages:

1) The present invention can greatly improve the surface polarity and printability of the polypropylene material by grafting and modifying the surface of a small amount of polar monomers. The critical condition of supercritical carbon dioxide is 31.4°C and 7.38MPa. Pure supercritical carbon dioxide fluid has high solubility, and a small amount of polar monomers and initiators can be dissolved in it; a small amount of acetone, or chloroform, or acetic acid The mixed system composed of ethyl ester, or toluene, or cyclohexane and carbon dioxide has better solubility for polar monomers and initiators above the critical point of carbon dioxide, thereby increasing the amount of polar monomers and initiators.

2) The supercritical carbon dioxide fluid has a strong diffusion ability. The polypropylene material or product is placed in the supercritical carbon dioxide fluid containing polar monomers and initiators, at 7.4MPa-15MPa, 32°C-100°C (pressure After soaking for 6 hours to 3 days, the polar monomer and initiator will diffuse from the surface of the polypropylene material to the surface and inside with carbon dioxide.

3) After the soaked polypropylene material is taken out, because carbon dioxide volatilizes quickly and carries out other solvents, there will be no carbon dioxide and solvent residues, while polar monomers and initiators remain on the surface of the polypropylene material.

4) The step (2) of the present invention is to graft the polypropylene material treated in the step (1). Wherein the grafting treatment is carried out by heating the polypropylene material treated in step (1), or ultraviolet irradiation treatment, or combined treatment of heating and ultraviolet irradiation. The initiator trapped in the surface layer of the polypropylene material generates free radicals when heated, or generates free radicals under the action of ultraviolet radiation, which initiates the grafting reaction between the polar monomers retained in the surface layer and polypropylene macromolecules, thereby improving the The surface energy of the polypropylene material improves the printability of the polypropylene material or product and the scratch resistance of the printed layer.

5) The present invention only treats the surface layer or surface of the polypropylene material, and the heat treatment temperature of step (2) is far lower than the melting point of polypropylene, or the ultraviolet irradiation time is short, therefore, the present invention can maintain polypropylene While the material has excellent comprehensive properties, its surface printability and scratch resistance of the printed layer are improved.

Detailed ways

In order to better understand the present invention, the present invention will be further described below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example 1

Add 3g of acrylic acid and 0.3g of dibenzoyl peroxide into a pressure vessel 1 with a volume of about 50ml, and pressurize carbon dioxide into the pressure vessel 1 with a pressure of 7.4MPa, and heat the vessel 1 at a temperature of 32°C. Roll a random copolymerized polypropylene (melt index: 6.5) sheet with a length of 20 cm, a width of 2 cm, and a thickness of 0.3 mm into a small roll along the length direction, and place it in a pressure-resistant container 2 with an inner diameter of 5 cm and an inner cavity height of 2.5 cm .

The fluid in the container 1 is injected into the pressure-resistant container 2 by a high-pressure pump, and the pressure in the pressure-resistant container 2 is 7.4 MPa and the temperature is 32 ° C by means of pressurization and heating, and the conditions are maintained for 3 days.

Open the pressure-resistant container 2, take out the random copolymerized polypropylene sheet, and place it at room temperature and normal pressure for 1 hour.

Put the above treated random copolymerized polypropylene sheet into an oven at 100°C for 20 minutes to obtain a modified sheet with a surface energy of 47.5 mN/m. The test method of surface energy is DIN 55660-2-2011; compared with the surface energy of unmodified PP material, it can be seen from Table 1 that compared with the surface energy of unmodified PP material, the surface energy after modification of this embodiment has a large improvement. Due to the high surface energy, the surface-modified random copolymer polypropylene sheet has good printability and scratch resistance of the printed layer.

Example 2

Add 2g of maleic anhydride and 0.2g of dicumyl peroxide into a pressure vessel 1 with a volume of about 50ml, and press carbon dioxide into the vessel 1 with a pressure of 15MPa, and heat the vessel 1 at a temperature of 80°C. The isotactic polypropylene (melt index is 3.0) film with a length of 20 cm, a width of 2 cm, and a thickness of 0.02 mm is rolled into a small roll along the length direction, and placed in a pressure-resistant container 2 with an inner diameter of 5 cm and an inner cavity height of 2.5 cm.

The fluid in the container 1 is injected into the container 2 by a high-pressure pump, and the pressure in the container 2 is 15 MPa and the temperature is 100 ° C by means of pressurization and heating, and the conditions are maintained for 3 days.

Open container 2, take out the isotactic polypropylene film, and place it at room temperature and pressure for 1 hour.

Put the treated isotactic polypropylene film in an oven at 130° C. for 30 minutes, and pass through nitrogen for protection to obtain a modified sheet with a surface energy of 48.7 mN/m.

Example 3

Add 2g of hydroxyethyl acrylate, 0.2g of benzophenone and 5g of cyclohexane into a pressure-resistant container 1 with a volume of about 50ml, and press carbon dioxide into the container 1 with a pressure of 12MPa, and heat the container 1 at a temperature of 80°C . The isotactic polypropylene (melt index is 3.0) film with a length of 20 cm, a width of 2 cm, and a thickness of 0.02 mm is rolled into a small roll along the length direction, and placed in a pressure-resistant container 2 with an inner diameter of 5 cm and an inner cavity height of 2.5 cm.

The fluid in the container 1 is injected into the container 2 by a high-pressure pump, and the pressure in the container 2 is 15 MPa and the temperature is 60 ° C by means of pressurization and heating, and the conditions are maintained for 6 days.

Open container 2, take out the isotactic polypropylene film, and place it at room temperature and normal pressure for 4 hours.

The above treated isotactic polypropylene film was irradiated with ultraviolet light with a wavelength near 360 nm for 1 min to obtain a modified sheet with a surface energy of 47.0 mN/m.

Table 1 summarizes the test results of the examples samples. Table 1 also shows the properties of the 0.3 mm thick random copolymer polypropylene sheet and the 0.02 mm thick isotactic polypropylene film before treatment.

Table 1

Embodiment 1 has carried out surface treatment to the random copolymer polypropylene sheet material of 0.3mm thick, and the surface energy of embodiment 1 sample is 47.5mN/m, and the random copolymer polypropylene sheet material of untreated 0.3mm thick Compared with the surface energy (29.6mN/m), there is a great improvement, while other main properties do not change much. Embodiment 2 and embodiment 3 have carried out surface treatment to the thick isotactic polypropylene film of 0.02mm, and the surface energy of embodiment 2 sample is 48.7mN/m, and the surface energy of embodiment 3 sample is 47.0mN/m, and not Compared with the surface energy (29.3mN/m) of the treated isotactic polypropylene film with a thickness of 0.02mm, it has been greatly improved, while other main properties have little change.

Claims (8)

1. a preparation method for printable polypropylene material, is characterized in that, comprises the steps:

1): polypropylene material being placed in to the supercritical carbon dioxide fluid that contains polar monomer and initiator, is that 7.4MPa ?15MPa, temperature are to soak after 6 hours to 3 days at 100 ℃ of 32 ℃ of ?at pressure, take out and under normal temperature and pressure, place 1 ?when little 4 hours; In described polar monomer and supercritical carbon dioxide fluid the mass ratio of carbonic acid gas be 1 ?10:100; The mass ratio of described initiator and polar monomer be 0.5 ?10:100;

Described polar monomer is maleic anhydride, vinylformic acid, methacrylic acid, vinyl acetate, Hydroxyethyl Acrylate, methacrylic ester hydroxy methacrylate.

Described initiator is dicumyl peroxide, di-t-butyl peroxide, di-isopropyl peroxydicarbonate, dibenzoyl peroxide, diphenyl peroxide dodecanoyl, Diisopropyl azodicarboxylate, 2,2'-Azobis(2,4-dimethylvaleronitrile), or benzophenone, 4,4 ’ ?dimethylaminobenzophenone, diethoxy acetophenone, dichlorobenzene ethyl ketone;

2): the polypropylene material after step (1) is processed is carried out to grafting processing.

2. the preparation method of printable polypropylene material according to claim 1, is characterized in that, described polypropylene material is isotatic polypropylene, Atactic Polypropelene or syndiotactic polypropylene.

3. the preparation method of printable polypropylene material according to claim 1, it is characterized in that, by percentage to the quality, described polypropylene material be add 1% ?4% ethene atactic copolymerized polypropene or add the block copolymerization polypropylene of 4% above ratio ethene.

4. the preparation method of printable polypropylene material according to claim 1, is characterized in that, the profile of described polypropylene material is film, sheet material, sheet material or fibrous.

5. the preparation method of printable polypropylene material according to claim 1, is characterized in that, the profile of described polypropylene material is fabric or non-woven fabrics shape.

6. the preparation method of printable polypropylene material according to claim 1, it is characterized in that, described supercritical carbon dioxide fluid, except carbonic acid gas, also comprises the mixed system that acetone, chloroform, ethyl acetate, toluene, hexanaphthene and carbonic acid gas form; The consumption of described acetone, chloroform, ethyl acetate, toluene, hexanaphthene and carbonic acid gas account for supercritical carbon dioxide systems quality 2% ?20%.

7. the preparation method of printable polypropylene material according to claim 1, is characterized in that, described grafting is treated to heat treated or uviolizing is processed or heating and uviolizing combined treatment.

8. the preparation method of printable polypropylene material according to claim 7, is characterized in that, the temperature of described heat treated be 60 ℃ ?130 ℃, the time be 10min ?60min; Described ultraviolet wavelength be 320nm ?450nm, ultraviolet irradiation time be 1min ?10min.