RU2707995C1 - Method of producing reinforced thermoplastic vibration-absorbing films and films obtained using said method - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method of producing reinforced thermoplastic vibration absorbing films used in composite vibration-absorbing materials intended for protection of various structures from vibration. Disclosed is a method of producing reinforced thermoplastic vibration absorbing film, which includes the following stages: mixing polyvinyl acetate or butyl acrylate or mixture thereof with one or more plasticizers; heating the obtained composition at temperature of 70–90 °C for at least 2 hours; continuous supply of said heated composition to extruder; continuous passage of said composition through an extruder at temperature of 120–150 °C; continuous supply of fused polymer composition through slit head of extruder in form of melted web on reinforcing material, which is continuously supplied to substrate on cooled roller, with formation of reinforced thermoplastic film.

EFFECT: present method enables to obtain reinforced self-adhesive films of low thickness (0,5–2 mm), having high dissipative properties, allowing to achieve a significant damping effect in composite vibration-absorbing materials, in particular, when used as an intermediate viscoelastic layer in composite metal structures or in laminar coatings.

12 cl, 2 tbl

Description

Technical field

The present invention relates to polymeric materials, and in particular relates to a method for producing reinforced thermoplastic vibration-absorbing films used in composite vibration-absorbing materials designed to protect various structures from vibration.

State of the art

The prior art method for producing a vibration-absorbing sheet, comprising the step of mixing polyvinyl acetate with a plasticizer and a mixture of solid inorganic fillers (see patent US3994845, publ. 30.11.1976). The resulting vibration-absorbing sheet has a sufficiently large thickness (from 1 to 12.5 mm).

A known method of producing a polymer vibration-absorbing material (see patent GB2167425A, publ. 05.29.1986), comprising the steps of mixing a vinyl acetate polymer with a plasticizer and a filler, heating the resulting composition to a temperature of 170-190 ° C and forming the final product, in particular by extrusion molding or passing through rollers heated to a temperature of 60-120 ° C.

EP0176306B1 (publ. 12/20/1989) discloses a method for producing a vibration-absorbing sheet of polymeric material, comprising the steps of mixing a vinyl acetate polymer with a plasticizer and a filler, then heating the resulting composition to a temperature of 170-190 ° C, which is then passed through special rollers heated to a temperature of 60-120 ° C, with the formation of the finished sheet.

US4783300A (publ. 11/08/1988) describes a method for producing a polymer sheet material having vibration and noise absorption properties, comprising the steps of continuously supplying polyvinyl acetate, a plasticizer and a mineral filler to the mixer, and then the resulting composition is continuously passed through a continuous mixer ( extruder), with the formation of a homogeneous mixture of the above components, then the resulting composition is heated to a temperature of 170-190 ° C (temperature in the extruder), the heated composition is continuously fed to and special rollers heated to a temperature of 60-120 ° C and continuously form sheets.

 A common disadvantage of the above methods is the use of a high content of fillers in the composition, which makes it possible to obtain hard vibration damping coatings that work effectively only with a sufficiently large thickness, at least 2 times greater than the thickness of the damped metal structure. In this case, even with such a ratio of coating thicknesses and damped structures in test tests, the loss coefficient for such hard vibration damping coatings does not exceed 0.2-0.4. When reducing the thickness of the coating, its effectiveness is significantly reduced. In addition, the processing of rigid polymer mixtures with a large amount of filler requires a significant increase in temperature to 170 ° C - 190 ° C. Since polyvinyl acetate when it is heated above 150 ° C is thermally decomposed with the release of acetic acid, even short heating at temperatures of 170 ° C-190 ° C gives the resulting materials a sharp unpleasant odor. It is impossible to obtain softer elastic materials by increasing the plasticizer content in the mixture formulation according to the proposed technology due to sticking of the sheet material on the rolls of the forming equipment.

Disclosure of invention

Thus, the problem to which the present invention is directed is to develop a method for producing reinforced thermoplastic films of small thickness (in the range of 0.5-2 mm) having high vibration-absorbing properties intended for use in composite vibration-absorbing materials.

The technical result consists in obtaining reinforced thermoplastic self-adhesive films of small thickness (within 0.5-2 mm) with high dissipative properties, which allow to achieve a significant damping effect in composite vibration-absorbing materials, in particular, when used as an intermediate viscoelastic layer in composite metal structures or in layered coatings.

The claimed technical result is achieved by implementing the method for producing a reinforced thermoplastic vibration-absorbing film, including the following steps, in which:

a) mixing the polymer or mixture of polymers with one or more plasticizers;

b) heat the resulting composition at a temperature of 70-90 ° C for at least 2 hours;

c) continuously supplying said heated composition to an extruder;

d) continuously passing the specified composition through the extruder at a temperature of 120-150 ° C;

f) the molten polymer composition is continuously fed through the slit head of the extruder in the form of a molten web onto a reinforcing material that is continuously fed on a substrate to a cooled roll to form a reinforced thermoplastic film.

The formulations selected experimentally in combination with the modes and conditions for the implementation of the method are the most optimal for producing thermoplastic films of various compositions with high vibration-absorbing properties in a wide temperature range.

In a first step of the process, the polymer or polymer blend is mixed with one or more plasticizers.

In a preferred embodiment, polyvinyl acetate (PVA) or polybutyl methacrylate (PBMA) is used as the thermoplastic polymer. In addition, in the inventive method can be used a mixture of these polymers.

In one preferred embodiment, the plasticizers are selected from the following classes of compounds: esters of dicarboxylic aromatic acids and aliphatic alcohols, esters of dicarboxylic aliphatic acids and aliphatic alcohols, esters of carboxylic acids and aliphatic alcohols, esters of phosphoric acid and aliphatic alcohols, ethers of phosphoric acids and g phosphoric acid and aromatic alcohols, halogen-substituted aliphatic compounds. The choice of plasticizer is determined by the compatibility of the plasticizer with the polymer, as well as its glass transition temperature. Depending on the type of plasticizer, as well as the quantitative ratio polymer: plasticizer, it is possible to obtain a thermoplastic film with the required temperature range for maximum vibration absorption.

The total weight of the composition may contain about 10-40% plasticizer. The specified amount of plasticizer is the most optimal for obtaining films in a wide temperature range of maximum vibration absorption.

In addition to the plasticizer, at the first stage, various fillers and additives can be introduced into the composition.

As fillers can be used mica, chalk, graphite, talc, aluminum hydroxide, glass sphere or soot. Fillers are used to improve film performance. However, with the introduction of a significant amount of fillers, the adhesive and vibration-absorbing properties of the film deteriorate, and the maximum temperature of vibration absorption is shifted to a higher temperature region. Therefore, fillers should be used in an amount of not more than 25% of the total weight of the composition.

Special additives in an amount of not more than 4%, in particular metal oxides or hydroxides, may be added to the polymer or polymer mixture with one or more plasticizers.

It should be noted that when implementing the method in step a) (when preparing the composition), all dry components should be homogenized first, and then liquid components should be added.

Next, the composition obtained in step a) is heated at a temperature of 70-90 ° C for at least 2 hours to “ripen” it. The specific “ripening” temperature depends on the composition: the higher the filler content, the higher the heating temperature should be.

Then the heated composition is continuously fed into a continuous mixer - an extruder heated to a temperature of 120-150 ° C. It should be noted that the choice of a specific temperature in the extruder depends on whether filler is used in the composition of the composition and what is its quantity. The higher the filler content, the higher the temperature should be.

 In the extruder, the polymer melts and further homogenizes the composition. Continuous feeding and passing the composition through the extruder prevents the material from burning in the extruder and ensures equal thickness of the resulting thermoplastic polymer film.

Then, the molten composition in the form of a molten web passed through the extruder is continuously fed through the slit head of the extruder to a receiving cooled roll, onto which a reinforcing material is also continuously fed, in particular a fiberglass, fiberglass or polymer mesh with 2-20 mm mesh size on the substrate. In this case, the melt of the composition is impregnated with fiberglass, fiberglass or polymer mesh, with the formation of a reinforced thermoplastic film with a thickness of 0.5-2 mm.

Reinforcing a thermoplastic film is necessary to improve the rheological characteristics of the film, reduce shrinkage, and reduce its fluidity under load. Reinforcement slightly reduces the coefficient of mechanical loss of the film, especially during tensile deformations, but with bending vibrations practically does not affect the vibration-absorbing properties of the film.

By varying the cell size and type of reinforcing material, a compromise can be found between the rheological and vibration-absorbing characteristics of the film, depending on the specific tasks and conditions of its use.

To prevent sticking, a reinforced film is released on the substrate.

In one embodiment of the invention, a temporary substrate is used which is removed by using a film in an article. As a temporary removable substrate can be used polyethylene or polypropylene film, or siliconized paper. The thickness of the temporary substrate is preferably 40-200 μm.

The resulting reinforced thermoplastic film on the substrate can be wound into rolls using a winding device. The film thickness is controlled by the number of revolutions of the screws of the extruder and the number of revolutions of the roll of the winding device.

Upon receipt of a thermoplastic reinforced film according to the method described above, an unremovable substrate, for example, from aluminum foil or foil paper, or polyvinyl chloride or sevylene or polyethylene terephthalate film, can be additionally used. In contrast to the temporary substrate, which is used for convenient transportation and storage of the thermoplastic film and is removed before the film is used in the product, the non-removable substrate is used in vibration-absorbing materials together with the thermoplastic film.

In the case of using an unremovable substrate, the hot melt of the composition during unloading from the extruder, impregnated with fiberglass, fiberglass or polymer mesh, adheres firmly to the unremovable substrate. To prevent sticking, a film with an additional layer from an unremovable substrate can also be produced on a temporary substrate.

By the method described above, it is possible to obtain single-layer reinforced thermoplastic films with a thickness of 0.5-1 mm with a given temperature region of maximum vibration absorption.

In addition, the proposed method can also be obtained two-layer reinforced thermoplastic films with a thickness of 1-2 mm with an expanded temperature region of effective vibration absorption.

To obtain two-layer films in step a), two compositions of different compositions are prepared, respectively, to obtain films with different temperature ranges for maximum vibration absorption.

Further, according to the above-described sequence of steps of the method, one of the obtained compositions gives a single-layer thermoplastic reinforced film having an additional non-removable substrate.

Then, the second composition obtained at the stage of mixing the components is continuously charged into the extruder, and the previously obtained single-layer reinforced film is continuously fed to the cooled receiving roll with the free side of the unremovable substrate upward. The melt of the second composition passed through an extruder in the form of a molten web is discharged onto the free side of an unremovable substrate of a single-layer reinforced thermoplastic film obtained from the first composition.

Thus, a bilayer reinforced film is obtained in which two thermoplastic layers of different composition are separated by an intermediate layer from an unremovable substrate. To prevent sticking, a two-layer film with an intermediate layer from an unremovable substrate can be produced on a temporary substrate. The obtained two-layer thermoplastic film has an expanded temperature region of effective vibration absorption and has a thickness in the range of 1-2 mm.

The invention also includes single-layer and two-layer reinforced thermoplastic films obtained by the above methods.

The films obtained by this method together have high loss coefficients in a wide temperature range from -15 ° C to + 75 ° C in the frequency range from 10 to 10,000 Hz. The temperature range of effective operation, covered by each single-layer film from this series, is ~ 30 °.

Embodiments of the invention

Example No. 1

45% of polyvinyl acetate is mixed with 23% of mica for 10 minutes, after which 32% of plasticizer (triacetin (TA)) is added, and stirred for another 3 minutes. Next, heat the resulting composition at a temperature of 90 ° C for at least 2 hours in a thermostat. Then, the extruder is heated to a temperature of 140 ° C and the specified heated composition is continuously fed and continuously passed through the extruder at a temperature of 140 ° C. At the exit of the extruder, a molten polymer composition in the form of a molten web is continuously fed through a slit head onto a fiberglass mesh with 10 mm mesh, which is continuously fed onto a cooled roll on a substrate of 80 μm thick plastic film. The obtained reinforced thermoplastic single-layer film is then fed to a winding device and wound into a roll. The revolutions of the extruder shaft and the winding device are selected so that the film thickness is maintained at a level of 0.5 mm.

Example No. 2

Obtaining a thermoplastic film in this case is carried out similarly to the method described in example 1, only at the first stage 60% polybutyl methacrylate is mixed with 40% tributyl phosphate (TBP). The resulting composition is heated in a thermostat at 70 ° C for at least 2 hours. The temperature in the extruder is 140 ° C. The molten composition is taken on fiberglass. The result is a single-layer film with a thickness of 1 mm on the substrate.

Example No. 3

Obtaining a thermoplastic film in this case is carried out similarly to the method described in example 1, only at the first stage 72% of polyvinyl acetate is mixed with 2% zinc oxide and 26% dibutyl phthalate (DBP). The resulting composition is heated in a thermostat at 80 ° C for at least 2 hours. The temperature in the extruder is 130 ° C. The molten composition is taken on a fiberglass mesh with 5mm cells. Get a single layer film with a thickness of 0.5 mm on the substrate.

Example No. 4

Obtaining a thermoplastic film in this case is carried out similarly to the method described in example 1, only at the first stage 48% of polyvinyl acetate is mixed with 24% polybutyl methacrylate and 28% trichloroethyl phosphate (TCEP). Next, the composition is heated at a temperature of 70 ° C for at least 2 hours. The resulting heated composition is then continuously fed and passed through an extruder at a temperature of 140 ° C. The molten composition is fed through a slit head to a fiberglass mesh with 10 mm cells. Get a single-layer reinforced film with a thickness of 0.5 mm on a substrate.

Example No. 5

Obtaining a thermoplastic film in this case is carried out similarly to the method described in example 1, only in the first stage, 90% polybutyl methacrylate and 10% dibutyl sebacinate (DBS) are mixed. Next, the composition is heated at a temperature of 80 ° C for 2 hours. The resulting heated composition is then continuously fed and passed through an extruder at a temperature of 120 ° C. The molten composition is fed through a slit head onto a polymer mesh with 2 mm cells. Get a single-layer reinforced film with a thickness of 1 mm on a substrate.

Example No. 6

Obtaining a thermoplastic film in this case is carried out similarly to the method described in example 2, only in the first stage 75% of polyvinyl acetate is mixed with 5% of tricresyl phosphate (TCF) and 20% chloroparaffin (CP). Next, the composition is heated at a temperature of 90 ° C for at least 2 hours. The resulting heated composition is then continuously fed and passed through an extruder at a temperature of 150 ° C. The molten composition is fed through a slotted head to a fiberglass mesh with 20 mm cells. Get a single-layer reinforced film with a thickness of 0.5 mm on a substrate.

Example No. 7

Get the film according to the method described in example 1, only additionally used non-removable substrate of aluminum foil with a thickness of 60 μm. Then prepare a composition similar in composition to that described in Example 3. This composition, after heating in a thermostat at a temperature of 80 ° C, is continuously passed through an extruder heated to 130 ° C. The previously received single-layer reinforced film with the free side of the foil upward on a 100 mm thick plastic film is continuously fed to a cooled receiving roll. The melt of the second composition passed through an extruder in the form of a molten web is discharged onto the free side of the foil of a single-layer reinforced thermoplastic film from the first composition. A bilayer reinforced thermoplastic film is obtained with an expanded temperature region of effective vibration absorption on a temporary substrate. The thickness of the two-layer reinforced film is 1 mm.

Example 8

A film is obtained by the method described in example 3, only additionally, an aluminum foil 60 μm thick is used as an unremovable substrate. Film thickness 1 mm. Then prepare a composition similar in composition to that described in Example 6. After heating in a thermostat at a temperature of 90 ° C, this composition is continuously passed through an extruder heated to 150 ° C. The previously received single-layer reinforced film with the free side of the foil upward on a polyethylene film is continuously fed to a cooled receiving roll. The melt of the second composition passed through an extruder in the form of a molten web is discharged onto the free side of the foil of a single-layer reinforced thermoplastic film from the first composition. A bilayer reinforced thermoplastic film with an expanded temperature region of effective vibration absorption is obtained. The thickness of the two-layer reinforced film is 2 mm.

Below is a summary table 1 for examples 1-8.

Table 1

Example Polymer Plasticizer Filler Additive Reinforcement T ° C heating T ° C extruder Film thickness mm T ° C max. ŋ
Max. one PVA Triacetin
32% Mica
23% Fiberglass mesh
10mm 90 140 0.5 +5 0.8 2 PBMA Tributyl phosphate
40% Fiberglass 70 140 1,0 -5 0.55 3 PVA Dibutyl phthalate
26% Zinc oxide
2% Fiberglass mesh
5mm 80 130 0.5 +25 0.82 4 PVA + PBMA Trichloroethyl phosphate
28% Fiberglass mesh
10mm 70 140 0.5 +25 0.52 5 PBMA Dibutylsebacinate
10% 2mm polymer mesh 80 120 1,0 +45 0.60 6 PVA Tricresyl phosphate
5%
Chloroparaffin 20% Fiberglass mesh
20 mm 90 150 0.5 +65 0.77 7 = 1 + 3 PVA 1,0 8 = 3 + 6 PVA 2.0

The films obtained in Examples 1-8 were tested by the method of stimulated resonance vibrations according to the adapted method from OST 1-90384-89. Considering that the films are intended for use in composite metal structures as an intermediate viscoelastic layer or in reinforced metal coatings, the coefficients of mechanical energy losses of bending vibrations of cantilevered three-layer metal-polymer samples were determined, in which metal rods 240 mm long, 8 mm wide were used as outer layers 1.5 mm thick, and as a viscoelastic polymer damping layer - thermoplastic obtained by the above method film. The determination of the coefficient of mechanical losses is based on measuring the width of the resonance maximum on the curve of the amplitude of the oscillations of the cantilevered sample on the frequency and temperature at a constant disturbing force. The coefficient of mechanical energy loss of the bending vibrations of steel rods damped by a film was calculated by the formula:

ŋ = ∆f / f _res.

where ∆f = f ₂ -f ₁ is the width of the resonant maximum, Hz;

f ₁ is the frequency below the resonance, at which the vibration level is 3 dB lower than at the resonance, Hz;

f ₂ - the frequency is higher than the resonance, at which the vibration level is 3 dB lower than at the resonance, Hz;

f _res - resonant frequency, Hz.

For this design, the first resonance lies in the region of 130-200 Hz.

The following is a summary table 2 on the properties of the films obtained in examples 1-8.

table 2

Examples
№№ Examples
composition Number of layers Total film thickness Loss coefficient at a given temperature -25 ° C -15 ° C -5 ° C + 5 ° С + 15 ° С + 25 ° С + 35 ° C + 45 ° C + 55 ° C + 65 ° C + 75 ° C + 85 ° C one PVA + TA + Mica one 0.5 0.35 0.65 0.80 0.64 0.25 2 PBMA + TBF one 1,0 0.25 0.4 0.55 0.42 0.32 3 PVA + DBP + ZnO one 0.5 0.25 0.67 0.82 0.7 0.32 4 PVA + PBMA + TCEF one 0.5 0.38 0.47 0.4 0.52 0.4 0.35 5 PBMA + DBS one one 0.35 0.55 0.60 0.32 6 PVA + TKF + HP one 0.5 0.35 0.64 0.77 0.5 0.25 7 Examples 1 + 3 2 1,0 0.3 0.62 0.75 0.66 0.70 0.6 0.32  8 Examples 3 + 6 2 2.0 0.20 0.6 0.98 0.75 0.6 0.7 0.86 0.4 0.2

As can be seen from table 2, the inventive method allows to obtain thermoplastic films with high vibration damping properties in a wide temperature range from -15 ° C to + 75 ° C.

In this case, the temperature range of effective vibration absorption is ~ 30 ° for single-layer films based on one polymer and about 60 ° for two-layer films. When mixing two polymers, it is possible, by selecting a plasticizer, to obtain single-layer films with an extended temperature range of effective vibration absorption, but in this case, while maintaining the film thickness, the level of loss coefficient decreases.

Claims (16)

1. A method of obtaining a reinforced thermoplastic vibration-absorbing film, comprising the following steps, in which: a) polyvinyl acetate, polybutyl methacrylate or a mixture thereof is mixed with one or more plasticizers; b) heat the resulting composition at a temperature of 70-90 ° C for at least 2 hours; c) continuously supplying said heated composition to an extruder; d) continuously passing the specified composition through the extruder at a temperature of 120-150 ° C; f) continuously feeding the molten polymer composition through the slit head of the extruder in the form of a molten web onto a reinforcing material selected from fiberglass, fiberglass or polymer mesh, which is continuously fed onto a substrate to a cooled roll, with the formation of a reinforced thermoplastic film. 2. The method according to claim 1, characterized in that the plasticizer is selected from the classes: esters of dicarboxylic aromatic acids and aliphatic alcohols, esters of dicarboxylic aliphatic acids and aliphatic alcohols, esters of carboxylic acids and aliphatic alcohols, esters of phosphoric acid and aliphatic alcohols, phosphoric acid esters and halogen-substituted aliphatic alcohols, esters of phosphoric acid and aromatic alcohols, halogen-substituted aliphatic compounds. 3. The method according to claim 2, characterized in that the amount of plasticizer is 10-40% of the total weight of the composition.
4. The method according to claim 1, characterized in that the composition further comprises one or more filler and additive. 5. The method according to claim 4, characterized in that mica, chalk, graphite, talc, carbon black, glass spheres or aluminum hydroxide are used as filler in an amount of not more than 25% of the total weight of the composition. 6. The method according to claim 4, characterized in that the additives used are metal oxides or hydroxides in an amount of not more than 4% of the total weight of the composition. 7. The method according to claim 1, characterized in that the mesh size of the fiberglass or polymer mesh is 2-20 mm 8. The method according to claims 1 to 7, characterized in that they use a temporary substrate made of polyethylene or polypropylene film or siliconized paper. 9. The method according to claim 1, characterized in that they use a non-removable substrate made of aluminum foil or foil paper, or polyvinyl chloride, or sevilen, or polyethylene terephthalate film. 10. The method according to claim 1, characterized in that in step a) two compositions of various compositions are prepared, after which a single-layer reinforced thermoplastic vibration-absorbing film is prepared from the first composition, further comprising an unremovable substrate, onto which then through the slotted head of the extruder in the form of a molten web a second composition continuously passed through steps b) to c) is continuously fed to form a two-layer reinforced thermoplastic film. 11. A single-layer reinforced thermoplastic vibration-absorbing film obtained by the method according to any one of paragraphs. 1-9, having a thickness of 0.5-1 mm. 12. A two-layer reinforced thermoplastic vibration-absorbing film obtained by the method of claim 10, having a thickness of 1-2 mm.