CN116254064A

CN116254064A - Polymer film

Info

Publication number: CN116254064A
Application number: CN202111505156.1A
Authority: CN
Inventors: 黄子荣
Original assignee: Chang Chun Petrochemical Co Ltd
Current assignee: Chang Chun Petrochemical Co Ltd
Priority date: 2021-12-10
Filing date: 2021-12-10
Publication date: 2023-06-13

Abstract

The present invention relates to a polymer film comprising a polyvinyl acetal resin and a plasticizer; wherein the polymer film is one or more layers and the temperature at which the lowest value of the loss factor of the polymer film occurs is 40 ℃ to 60 ℃. The polymer film provided by the invention has good fluidity and processability.

Description

Polymer film

[ field of technology ]

The present invention relates generally to a polymer film body; the invention relates in particular to a polymer film suitable for an intermediate film of laminated glass.

[ background Art ]

The polymer film has wide application in the current society, and the prepared material is quite diverse, the polymer film has good film forming property, and can have the excellent characteristics of high transparency, elasticity, toughness, strong alkali resistance, oil resistance, flexibility, weather resistance, low-temperature impact resistance and the like according to the adjustment of raw materials or manufacturing procedures. Common materials for polymer films such as polyvinyl acetal resin have a specific chemical structure, so that the polymer film has excellent adhesion to glass, metal, ceramic powder, plastic, leather, wood and the like; in addition, the polyvinyl acetal resin has good dispersibility for pigments and dyes and excellent compatibility with various resins.

In the application aspect, the polymer film made of the polyvinyl acetal resin can be a single-layer film, a multi-layer film or an intermediate film sandwiched between glass. However, before the end product is produced, the polyvinyl acetal resin film sheet is subjected to a number of processing steps, such as film-spreading or cutting, which involve deformation. Accordingly, whether or not the polyvinyl acetal resin film has excellent processability becomes an important index.

In particular, the processability of the polymer is highly correlated with the viscoelastic properties; by viscoelastic is meant the reversible and irreversible deformation modulus of a material upon deformation. Further, parameters related to viscoelastic properties include loss factor (tan delta) values, also referred to as loss factor, damping factor or loss tangent, and glass transition temperature (glass transition temperature, tg) corresponding thereto, to express damping characteristics in viscoelastic properties of materials, and may be equivalent to the ratio of loss modulus (G ") to storage modulus (G') of materials; in contrast, the peak value of the temperature corresponding to the loss factor is the glass transition temperature, which can be regarded as the temperature at which the substance is reversibly transformed between a glassy state (which means that the material is in a state of low fluidity) and a highly elastic state (which means that the material is in a state of high fluidity and softness).

[ invention ]

This summary is intended to provide a simplified summary of the invention in order to provide a basic understanding of the invention to a reader. This summary is not an extensive overview of the invention and is intended to neither identify key or critical elements of the embodiments of the invention nor delineate the scope of the invention.

The inventors have found that the viscoelastic properties exhibited by a polymer film under the temperature conditions at the time of its processing have a further correlation with its processability, and that a polymer film having better processability should be obtained by controlling the viscoelastic properties under the temperature conditions. As an intermediate film for laminated glass, a polyvinyl acetal film is subjected to a film stretching process which stretches the film into a desired shape. If the film is too hard, the film is difficult to stretch at the rear end because of being difficult to stretch; too soft results in grain collapse during film stretching, so that the viscoelastic properties of the film at 40 to 60 ℃ are critical for smooth processing. Accordingly, the present invention improves flowability and processability of a polymer film by defining a temperature range in which the polymer film has a minimum value of loss factor (tan delta).

Specifically, in one aspect, the present invention provides a polymer film comprising a polyvinyl acetal resin and a plasticizer, wherein the polymer film is one or more layers, and the polymer film has a temperature at which a loss factor minimum occurs of 40 ℃ to 60 ℃.

According to an embodiment of the invention, the loss factor minimum is 0.13 to 0.19.

According to one embodiment of the invention, in the case of a layer, the lowest value of the loss factor occurs at a temperature greater than its glass transition temperature; or in the case of multiple layers, the lowest value of the loss factor occurs at a temperature greater than its maximum glass transition temperature.

According to one embodiment of the invention, the polyvinyl acetal resin is polyvinyl butyral (Polyvinyl Butyral, PVB).

According to an embodiment of the invention, the thickness of the polymer film is 0.2mm to 2mm.

According to an embodiment of the present invention, the polymer film has a heat shrinkage (%) ((length before heating-length after heating)/length before heating X100) of 2% to 5% at 50 ℃ for 1 hour.

According to one embodiment of the invention, the polymer film has an elongation of 220% to 300% as measured according to ASTM D412.

According to an embodiment of the present invention, in the case of one layer, the hydroxyl group content ratio of the polyvinyl acetal resin of the polymer film is 27mol% to 31mol%, and/or the acetalization degree of the polyvinyl acetal resin is 68mol% to 72mol%.

According to an embodiment of the present invention, in the case of one layer, wherein the polyvinyl acetal resin of the polymer film is used in an amount of 30 to 60 parts by weight per 100 parts by weight of the plasticizer.

According to one embodiment of the present invention, in the case of one layer, the polymer film is a head-up display (HUD) film.

According to one embodiment of the invention, the polymer film has a thick end and a thin end having a thickness thinner than the thick end.

According to one embodiment of the present invention, in the case of multiple layers, the polymer film has a three-layer structure, and the upper and lower layers are protective layers and sandwich an intermediate layer.

According to an embodiment of the present invention, the polyvinyl acetal resin of the protective layer has a hydroxyl group content ratio of 27mol% to 31mol%, and/or an acetalization degree of 68mol% to 72mol%.

According to an embodiment of the present invention, the plasticizer is 30 to 60 parts by weight based on 100 parts by weight of the polyvinyl acetal resin of the protective layer.

According to an embodiment of the present invention, the polyvinyl acetal resin of the intermediate layer has a hydroxyl group content ratio of 22mol% to 27mol%, and/or an acetalization degree of 62mol% to 68mol%.

According to an embodiment of the present invention, the plasticizer is 60 to 90 parts by weight per 100 parts by weight of the polyvinyl acetal resin of the intermediate layer.

According to an embodiment of the present invention, the polymer film is used as an intermediate film for laminated glass, and has a thickness of 0.5 to 2mm.

According to one embodiment of the invention, the thickness of the polymer film is 0.8mm and the thickness of the protective layer/interlayer/protective layer is 0.335mm/0.13mm/0.335mm.

The invention provides the following advantages: the polymer film provided by the invention is defined based on the characteristics, and further has more excellent processability and flowability.

[ description of the drawings ]

The foregoing and other objects, features, advantages and embodiments of the invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

FIGS. 1-3 are cross-sectional views of polymer films according to various embodiments of the present invention;

fig. 4-5 are flowcharts of polymer film fabrication according to various embodiments of the present invention.

Various features and elements are not drawn to scale in accordance with conventional practice in the drawings in a manner that best serves to illustrate the specific features and elements that are pertinent to the present invention. In addition, like components and parts are designated by the same or similar reference numerals among the different drawings.

[ detailed description ] of the invention

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to embodiments of the invention and specific examples, but will be used to describe the same. In this specification and the claims that follow, except where the context requires otherwise, the word "a" or "an" will be understood to mean a plurality. In addition, in this specification and the claims that follow, unless otherwise indicated, "disposed on" or "disposed on" can be construed as directly or indirectly contacting a surface of something, the definition of which should be construed as meaning in the context of the preceding and following paragraphs and ordinary skill in the art to which this specification pertains.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain standard deviations found in their respective testing measurements. As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1% or 0.5% of a particular value or range. Alternatively, the term "about" means that the actual value falls within an acceptable standard deviation of the average value, as determined by those of ordinary skill in the art to which the present invention pertains. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the present specification and attached claims are approximations that may vary depending upon the desired properties. At least these numerical parameters should be construed as the number of significant digits and by applying ordinary rounding techniques.

The present invention provides a polymer film comprising a polyvinyl acetal resin and a plasticizer. Specifically, the polyvinyl acetal resin described herein refers to a resin composition obtained by condensing polyvinyl alcohol with an aldehyde; wherein the polyvinyl alcohol can be obtained by saponifying a polyvinyl ester, and the saponification degree of the polyvinyl alcohol is generally in the range of 70 mol% to 99.9 mol%, for example: 70 mole%, 75 mole%, 80 mole%, 85 mole%, 90 mole%, 95 mole%, 99 mole%, or 99.9 mole%. The above aldehydes may generally employ aldehydes having 1 to 10 carbon atoms, for example: formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-ethylbutyraldehyde, n-caproaldehyde, n-caprylic aldehyde, n-pelargonic aldehyde, n-capric aldehyde, benzaldehyde and the like; preferably, the aldehyde is propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexanal or n-valeraldehyde; more preferably propionaldehyde, n-butyraldehyde or isobutyraldehyde. According to one embodiment of the invention, the polyvinyl acetal is polyvinyl butyral (Polyvinyl Butyral, PVB).

On the other hand, the plasticizers, also known as plasticizers, are often used in combination with polyvinyl acetal resins to affect the viscoelastic properties of the material. In particular, the plasticizer is selected from the group consisting of, without limitation, monoacids, polyacids, organic phosphoric acids, and organic phosphorous acids; the plasticizer is more specifically selected from the group consisting of triethylene glycol bis (2-ethylhexanoate) (triethylene glycol bis (2-ethylhexanoate), 3 GO), tetraethylene glycol bis (2-ethylhexanoate), triethylene glycol bis (2-ethylbutyrate), tetraethylene glycol bis (2-ethylbutyrate), triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate, dioctyl adipate, hexyl cyclohexyl adipate, diisononyl adipate, heptyl nonyl adipate, dibutyl sebacate, bis [2- (2-butoxyethoxy) ethyl adipate ], poly (adipate), propylene glycol dibenzoate, dipropylene glycol dibenzoate, tripropylene glycol dibenzoate, polypropylene glycol dibenzoate, 2, 4-trimethyl-1, 3-pentanediol dibenzoate, isodecyl benzoate, 2-ethylhexyl benzoate, diisononyl phthalate, dibutoxyethyl terephthalate, castor oil, methyl ricinoleate, soybean oil, and epoxidized soybean oil.

The polymer film provided by the invention is a one-layer or multi-layer structure, and the lowest value of loss factor occurs at a temperature of 40 ℃ to 60 ℃, for example but not limited to: 42.28 ℃, 48.29 ℃, 49.77 ℃, 51.43 ℃, 52.23 ℃, 54.21 ℃, 56.18 ℃, 58.27 ℃ or 59.14 ℃.

The loss factor is tan delta (or called loss factor, damping factor, loss tangent) to express damping characteristics in viscoelastic properties of a material, and can be equivalent to the ratio of the loss modulus (or called loss modulus, viscous modulus, G ") to the storage modulus (or called elastic modulus, G') of the material. Without being limited by a particular theory, the loss factor may have a minimum value that represents the energy being stored primarily; however, after passing this low temperature, the energy is gradually transferred to consumption, and at this time, the viscosity starts to increase. Thus, the processing requirements can be met by adjusting the low point, for example: if this low point is less than the processing temperature, the film will break because the film is too soft; conversely, if the low point is greater than the processing temperature, the film will be too ductile to be easily stretched.

According to some embodiments of the invention, the loss factor is at a minimum of 0.13 to 0.19, such as but not limited to: 0.138, 0.141, 0.144, 0.149, 0.151, 0.174, 0.177, 0.179 or 0.181. According to some embodiments of the invention, the polymer film is a monolayer film structure and has a Tg, and the temperature at which the lowest value of the loss factor occurs is greater than the Tg; according to other embodiments of the present invention, the polymer film is a multilayer film body structure and has a maximum Tg, and the temperature at which the lowest value of the loss factor occurs is greater than the maximum Tg. As used herein, tg refers to the glass transition temperature, which refers to the temperature at which a substance reversibly converts between a glassy state (meaning that the material is in a low-mobility state) and a highly elastic state (meaning that the material is in a high-mobility, soft state); further, the temperature at which the loss factor generates the peak value is the glass transition temperature.

The hydroxyl group content ratio of the polyvinyl acetal resin described herein means a molar fraction obtained by dividing the amount of ethylene groups bonded to hydroxyl groups by the total amount of ethylene groups in the main chain, expressed as a percentage. The acetalization degree (or acetalization degree) of a polyvinyl acetal resin described herein means a molar fraction obtained by dividing the amount of ethylene bonded to an acetal group by the total amount of ethylene in a main chain, expressed as a percentage. The degree of acetylation (or degree of acetylation) of the polyvinyl acetal resin is a value expressed as a percentage, which is a molar fraction obtained by subtracting the amount of ethylene bonded to a hydroxyl group and the amount of ethylene bonded to an acetal group from the total amount of ethylene in the main chain and dividing the obtained value by the total amount of ethylene in the main chain.

The hydroxyl group content ratio, the acetalization degree and the acetylation degree are calculated from the results of the "molar polyvinyl butyral test method" measurement according to JIS K6728.

Figures 1-3 are cross-sectional views of polymer films according to various embodiments of the present invention. The different embodiments are presented to respectively express different structural aspects of the polymer film of the present invention; specifically, the polymer film provided by the invention can be a single-layer film structure (shown in fig. 1), a three-layer film structure (shown in fig. 2) and a wedge-shaped film structure (shown in fig. 3). However, those skilled in the art may adjust or modify the content of the structural aspects as desired without departing from the central concept of the present invention.

Single layer film

Referring to fig. 1, the present invention provides a polymer film 100A having a layer 101. The thickness of the layer 101 is preferably 0.2 to 2mm, more preferably 0.38 to 1.52mm, such as but not limited to: 0.38, 0.76 or 1.52mm. The glass transition temperature of the layer 101 may be 10 to 35 ℃, preferably 25 to 35 ℃, more preferably 28 to 33 ℃, but the present invention is not limited thereto.

In the polymer film 100A provided in the present invention, the layer body 101 contains the polyvinyl acetal resin in a hydroxyl group content ratio of 26 to 31mol%, preferably 27.1 to 29.6mol%, for example, but not limited to: 27.1, 27.4, 27.5 or 29.6mol%. The layer body 101 contains a polyvinyl acetal resin having an acetalization degree of 68 to 73mol%, preferably 69.4 to 71.9mol%, such as, but not limited to: 69.4, 71.5, 71.6 or 71.9mol%. The degree of acetylation of the polyvinyl acetal resin contained in the layer 101 is 0.1 to 3.0mol%, preferably 1.0mol%, but the present invention is not limited thereto.

In the polymer film 100A provided in the present invention, the polyvinyl acetal resin contained in the layer body 101 may have a bulk specific gravity of 0.200 to 0.300, preferably 0.240 to 0.260, more preferably 0.249 to 0.258, but the present invention is not limited thereto. The bulk specific gravity described herein is measured in accordance with JIS K6720.

In the polymer film 100A provided in the present invention, the polyvinyl acetal resin contained in the layer body 101 may have a number average molecular weight (Mn) of 90,000 to 125,000, preferably 105,000 to 120,000, more preferably 106,250 to 115,200, but the present invention is not limited thereto.

Three-layer film

Referring to fig. 2, the present invention provides a polymer film 100B, which has a structure in which an intermediate layer 102 is sandwiched between upper and lower protective layers 104; however, in addition to the three-layer structure, a person having ordinary skill in the art can add a fourth, fifth or sixth layer according to the requirement; and is also preferably formed by alternating layers of intermediate layers and protective layers. Specifically, the thickness of the intermediate layer 102 is preferably 0.11 to 0.15mm, more preferably 0.13mm; the thickness of the protective layer 104 is preferably 0.32 to 0.35mm, more preferably 0.335mm; the thickness of the polymer film 100B is preferably 0.5 to 2mm, more preferably 0.75 to 0.85mm, for example: 0.75, 0.76, 0.77, 0.78, 0.8, 0.82 or 0.85mm. In a preferred embodiment, the polymer film is a three-layer structure, the upper and lower layers being protective layers and sandwiching an intermediate layer, which is an intermediate film for laminated glass.

In the polymer film 100B provided by the present invention, the glass transition temperature of the intermediate layer 102 may be-10 to 6 ℃, preferably-8 to 0 ℃, more preferably-7 to-2 ℃, but the present invention is not limited thereto; the glass transition temperature of the protective layer 104 may be 10 to 35 ℃, preferably 25 to 35 ℃, more preferably 28 to 33 ℃, but the invention is not limited thereto.

In the polymer film 100B provided in the present invention, the intermediate layer 102 contains the polyvinyl acetal resin in a hydroxyl group content ratio of 22 to 27mol%, preferably 23.8 to 26.2mol%, for example, but not limited to: 23.8, 24.9 or 26.2mol%. The polyvinyl acetal resin contained in the intermediate layer 102 has an acetalization degree of 62 to 68mol%, preferably 63.3 to 67.6mol%, for example, but not limited to: 63.3, 63.7 or 67.6 mole%. The polyvinyl acetal resin contained in the intermediate layer 102 has an acetyl degree of 7 to 13 mol%, for example, but not limited to: 8.6, 10.5 or 11.4mol%, but the invention is not limited thereto. On the other hand, the protective layer 104 contains a polyvinyl acetal resin having a hydroxyl group content of 26 to 31mol%, preferably 27.4 to 30.1mol%, such as, but not limited to: 27.4, 27.8 or 30.1mol%. The protective layer 104 contains a polyvinyl acetal resin having an acetalization degree of 68 to 73mol%, preferably 68.9 to 71.6mol%, such as, but not limited to: 68.9, 71.2, or 71.6 mole%. The degree of acetylation of the polyvinyl acetal resin contained in the protective layer 104 is 0.1 to 3.0mol%, preferably 1.0mol%, but the present invention is not limited thereto.

In the polymer film 100B provided by the present invention, the polyvinyl acetal resin contained in the intermediate layer 102 may have a bulk specific gravity of 0.200 to 0.300, preferably 0.240 to 0.260, more preferably 0.247 to 0.258, but the present invention is not limited thereto; the polyvinyl acetal resin contained in the protective layer 104 may have a bulk specific gravity of 0.200 to 0.300, preferably 0.240 to 0.260, more preferably 0.251 to 0.257, but the present invention is not limited thereto.

In the polymer film 100A provided by the present invention, the polyvinyl acetal resin contained in the intermediate layer 102 may have a number average molecular weight (Mn) of 100,000 to 280,000, preferably 120,000 to 250,000, more preferably 150,000 to 225,000, but the present invention is not limited thereto; the number average molecular weight (Mn) of the polyvinyl acetal resin contained in the protective layer 104 may be 90,000 to 125,000, preferably 105,000 to 120,000, more preferably 107,950 to 112,000, but the present invention is not limited thereto.

Wedge-shaped film

Referring to fig. 3, the present invention provides a polymer film 100C. According to some embodiments of the invention, the polymer film 100C may be used as a head-up display (HUD) film. Specifically, in order to avoid overlapping of projection images when the polymer film 100C is used as a HUD film, a thick end and a thin end with a thickness thinner than the thick end are respectively provided at both ends of the film body. The thin end has a thickness T ₁ While the thick endHas a thickness T ₂ The method comprises the steps of carrying out a first treatment on the surface of the The thickness T ₁ 0.7 to 0.8mm, preferably 0.76mm; and the thickness T ₂ From 1.4 to 1.5mm, preferably 1.45mm. Further, the polymer film 100C is illustrated as a film body structure that exhibits a wedge shape overall and a width W ₁ Is 1200mm.

In the polymer film 100C provided by the present invention, the polymer film 100C contains a polyvinyl acetal resin in a range similar to that of the above-described examples of the single-layer film, and the polymer film 100C contains a polyvinyl acetal resin having a hydroxyl group content ratio of 26 to 31mol%, preferably 28.3 to 28.7mol%, for example, but not limited to: 28.3 or 28.7mol%; the polymer film 100C contains the polyvinyl acetal resin having an acetalization degree (mol%) of 68 to 73mol%, preferably 70.3 to 70.7mol%, such as, but not limited to: 70.3 or 70.7mol%; while the degree of acetylation (mol%) of the polyvinyl acetal resin contained in the polymer film 100C is 0.1 to 3.0mol%, preferably 1.0mol%, the present invention is not limited thereto.

Process for producing polymer film

Fig. 4-5 are flow charts of polymer film fabrication, each showing a different embodiment of the present invention. Referring to fig. 4, a polymer film manufacturing process is provided for forming the single-layer film and the wedge-shaped film as described above; the flow at least comprises steps S100 to S102.

Specifically, in step S100, a polyvinyl acetal resin and a plasticizer are kneaded to form a resin composition. Wherein the plasticizer is preferably 30 to 60 parts by weight per 100 parts by weight of the polyvinyl acetal resin; more preferably, the plasticizer is 35 to 45 parts by weight, for example: 35. 36, 37, 38, 39, 40, 41, 42, 43, 44 or 45 parts by weight. On the other hand, the operation temperature and the rotation speed during the mixing process can be adjusted according to the conventional methods and requirements, and the detailed conditions are not limited in the present disclosure.

In step S102, the resin composition is made into a polymer film. The preparation method can be carried out by adopting a conventional film preparation mode, for example: extrusion molding or hot press molding. Further, fine tuning may be performed in this step depending on the polymer film pattern being produced; for example: can be specifically tailored to produce single layer films or wedge films that differ in geometric parameters.

Referring back to fig. 5, the polymer film manufacturing process provided herein is used to make the three-layer film pattern as described above; the flow at least comprises steps S200 to S206.

Specifically, in step S200, the first polyvinyl acetal resin and the plasticizer are kneaded to form a first resin composition. Wherein the plasticizer is preferably 60 to 90 parts by weight based on 100 parts by weight of the first polyvinyl acetal resin; more preferably, the plasticizer is 60 to 70 parts by weight, for example: 60. 61, 62, 63, 64, 65, 66, 67, 68, 69 or 70 parts by weight. On the other hand, the operation temperature and the rotation speed during the mixing process can be adjusted according to the conventional methods and requirements, and the detailed conditions are not limited in the present disclosure.

In step S202, a second polyvinyl acetal resin and a plasticizer are kneaded to form a second resin composition; wherein the plasticizer is preferably 30 to 60 parts by weight per 100 parts by weight of the polyvinyl acetal resin; more preferably, the plasticizer is 35 to 45 parts by weight, for example: 35. 36, 37, 38, 39, 40, 41, 42, 43, 44 or 45 parts by weight. On the other hand, the operation temperature and the rotation speed during the mixing process can be adjusted according to the conventional method, and the detailed conditions are not limited in the present invention.

In step S204, the first resin composition and the second resin composition are formed into a first layer and a second layer, respectively; the preparation method can be carried out by adopting a conventional film preparation mode, for example: extrusion molding or hot press molding. In step S206, the first layer and the second layer are combined to form a polymer film; wherein the first layer serves as an intermediate layer and the second layer serves as a protective layer. Alternatively, the method of manufacture may be carried out in conventional film preparation, for example: extrusion molding or hot press molding. According to at least one embodiment, step S204 and step S206 may be to extrude the second resin composition (as a protective layer) and the first resin composition (as an intermediate layer) in a T-die co-extrusion manner to form an intermediate film having a three-layer structure, wherein the intermediate film has a protective layer/intermediate layer/protective layer structure.

Determination of molecular weight of polyvinyl acetal resin

The molecular weight distribution of the polyvinyl acetal resin was measured by gel permeation chromatography (gel permeation chromatography, GPC), in which the polyvinyl acetal resin was dissolved in Tetrahydrofuran (THF), GPC analysis was performed under the following conditions, and the molecular weight thereof was calculated at a ratio corresponding to the area of polystyrene standards (Waters PS STD).

The device comprises: waters 1515PUMP system

The detector comprises: waters 2414RI

The brewing conditions are as follows: 1.0 milliliter/minute (mL/min), THF

And (3) pipe column: waters Styragel HR5 THF, waters Styragel HR THF, waters Styragel HR THF, waters Styragel HR1 THF

The polymer film manufactured by the above process can be used as a film to be tested for the following various characteristics.

Determination of viscoelastic Properties

The method for determining viscoelastic properties herein comprises at least the following steps: firstly, cutting a membrane to be measured into a round shape with the diameter of 8mm, and placing the membrane to be measured in a constant temperature and humidity box for 24 hours, and further regulating the temperature and the relative humidity of the membrane to be measured to be kept at 23 ℃ and 55% respectively. It should be noted that the step of cutting into a circular shape is performed according to the middle of the width direction of the film to be tested.

Subsequently, the film to be measured was placed in a rotary shear rheometer (Discovery Hybrid Rheometer II, DHR) (manufactured by TA Instrument) and analyzed for viscoelastic properties by an oscillation method under the following conditions: the test temperature is reduced from 100 ℃ to-20 ℃ and the cooling rate is 3 ℃/min; the oscillation frequency is set to 1Hz; maintaining the membrane to be measured at a strain of 1%; the clamp pressure was set to 1N. The loss factor and the glass transition temperature of the membrane to be measured are obtained from the analysis result by the method.

Measurement of Heat shrinkage

The method used herein to determine heat shrinkage is based on the following instrumentation:

heating oven (model: binder FD-115W)

Thermal circulation oven

Ruler device (precision 1 mm)

The method for measuring the heat shrinkage comprises at least the following steps: cutting the diaphragm to be measured into a square, wherein the side length of the square is 17cm, and drawing a square marking line of 15cm in the diaphragm to be measured; then, the membrane to be measured is suspended in an oven with the temperature set to 50 ℃ for 1 hour, and then is taken out and placed in the room temperature environment for 1 hour; and finally, measuring the thermal shrinkage rate of the film to be measured.

The calculation method for the thermal shrinkage rate comprises the following steps: heat shrinkage (%) = (length before heating-length after heating)/length before heating x 100. Without being limited by a specific theory, the higher the calculated thermal shrinkage rate value result is, the more the membrane to be measured is biased to a state of high fluidity and softness; the lower the heat shrinkage value, the more the film to be measured is biased to a state of low fluidity and hardness. According to at least one embodiment, the film to be tested may be considered to have good workability if the film to be tested exhibits a heat shrinkage in the range of 2-5% when heat treated at 50 ℃ for 1 hour.

Determination of elongation

The method used herein for measuring elongation is in accordance with ASTM D412, and the instrument used is an AI-7000M tensile tester manufactured by GOTECH. Specifically, the method comprises at least the following steps: the film to be tested is placed in an environment with a relative humidity of 23% and a temperature of 23℃for 2 hours.

The calculation method for the elongation comprises the following steps: elongation (%) = (length after stretching-length before stretching)/length before stretching ×100. According to at least one embodiment, the film to be tested may be considered to have good workability if the elongation value exhibited by the film to be tested is in the range of 220% to 300%. If the elongation is more than 300%, the film is easy to deform in the film spreading process; if the elongation is less than 220%, the stretching is difficult due to the difficulty in stretching the film during use.

Examples 1 to 9

The present invention provides the polymer films of examples 1 to 9 according to the above, wherein the polymer films are prepared by different parameters to generate different characteristics; further, analysis was made with respect to the viscoelastic properties, heat shrinkage and elongation characteristics of the polymer film. The detailed parameter definitions and the characteristic analysis results of examples 1 to 9 are shown in table 1.

The preparation methods of the polymer films of examples 1 to 9 are briefly described below:

preparation of a resin composition for protective layer: 100 parts by weight of a first polyvinyl acetal resin (illustratively, PVB resin) and 35 to 45 parts by weight of a plasticizer (illustratively, 3 GO) were thoroughly kneaded using a kneader to obtain a resin composition for a protective layer.

Preparation of resin composition for intermediate layer: 100 parts by weight of a second polyvinyl acetal resin (illustratively, PVB resin) and 60 to 70 parts by weight of a plasticizer (illustratively, 3 GO) were thoroughly kneaded using a kneader to obtain a resin composition for an interlayer.

Preparing a film body: examples 1 to 4 the resin composition for protective layer was extruded into a single layer film with a thickness of 0.38 to 1.52mm using an extruder; examples 5 and 6 were in the form of wedge-shaped films (i.e., HUD films) which were extruded to a thickness of 1.45mm and 0.76mm, respectively, using an extruder to give the resin composition a thickness of about 1200mm; in examples 7 to 9, the resin composition for protective layer and the resin composition for intermediate layer were extruded in the form of a three-layer film having a thickness of 0.8mm and a structure of protective layer/intermediate layer/protective layer (thickness: 0.335mm/0.13mm/0.335 mm) by means of coextrusion in a T die.

Comparative examples 1 to 8

Polymer films of comparative examples 1 to 9 were prepared in a similar manner to examples 1 to 9, except for the differences shown in table 2; further, analysis and evaluation methods were conducted with respect to the viscoelastic properties, heat shrinkage and elongation characteristics of the polymer film, as in examples 1 to 9.

It should be noted that comparative examples 1 to 4 are in the form of a single-layer film; comparative examples 5 and 6 were in the form of wedge-shaped films (i.e., HUD films); and comparative examples 7 to 8 were in the form of three films with an intermediate layer sandwiched between upper and lower protective layers. The detailed parameter definitions and the characteristic analysis results of comparative examples 1 to 8 are shown in table 2.

TABLE 1

TABLE 2

As can be seen from tables 1 and 2, the polymer films of examples 1 to 9, whether they were single-layer films or multi-layer films, exhibited better flowability and processability than those of comparative examples 1 to 8 by controlling the temperature at which the lowest value of the loss factor of the polymer films occurs to 40 ℃ to 60 ℃. As can be further understood from table 2, the temperature at which the lowest loss factors of comparative examples 1,3, 5 and 7 occur is less than 40 ℃, their heat shrinkage is greater than 5%, and elongation is greater than 300%, showing that the polymer films of comparative examples 1,3, 5 and 7 are too soft to deform or break during film stretching; the polymer films of comparative examples 2,4, 6 and 8 were too ductile to be easily developed, as shown by the fact that the minimum loss factors of comparative examples 2,4, 6 and 8 were all at a temperature of more than 60 ℃, the heat shrinkage of the films were less than 2%, and the elongation of the films were all less than 220%.

In summary, the present invention provides a polymer film comprising a polyvinyl acetal resin and a plasticizer; wherein the polymer film is one or more layers and the temperature at which the lowest value of the loss factor of the polymer film occurs is 40 ℃ to 60 ℃. The polymer film provided by the invention has good fluidity and processability.

Unless defined otherwise herein, scientific and technical terms used in connection with the present application shall have the ordinary meaning as understood by one of ordinary skill in the art. Furthermore, unless the context requires otherwise, the singular shall include the plural and the plural shall include the singular.

While the invention has been described in detail in connection with the preferred embodiments thereof, it should be understood that the invention is not limited thereto, but is intended to cover modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

[ symbolic description ]

100A to 100C polymer film

101 layer body

102 intermediate layer

104 protective layer

W ₁ Width of

T ₁ ,T ₂ Thickness of (A)

S100-S102, S200-S206.

Claims

1. A polymer film comprising a polyvinyl acetal resin and a plasticizer, and said polymer film being one or more layers, said polymer film having a temperature at which a loss factor minimum occurs of from 40 ℃ to 60 ℃.

2. The polymer film of claim 1, wherein the loss factor minimum is from 0.13 to 0.19.

3. The polymer film of claim 2, wherein in the case of a layer, the lowest value of the loss factor occurs at a temperature greater than its glass transition temperature; or in the case of multiple layers, the lowest value of the loss factor occurs at a temperature greater than its maximum glass transition temperature.

4. The polymer film of claim 1, wherein the polyvinyl acetal resin is polyvinyl butyral.

5. The polymer film of claim 1 having a thickness of 0.2mm to 2mm.

6. The polymer film according to claim 1, which has a heat shrinkage of 2% to 5% at 50 ℃ for 1 hour.

7. The polymer film of claim 1 having an elongation of 220% to 300% as measured according to ASTM D412.

8. The polymer film according to claim 1, wherein in the case of one layer, the hydroxyl group content ratio of the polyvinyl acetal resin of the polymer film is 27mol% to 31mol%, and/or the acetalization degree of the polyvinyl acetal resin is 68mol% to 72mol%.

9. The polymer film according to claim 1, wherein the plasticizer is 30 to 60 parts by weight per 100 parts by weight of the polyvinyl acetal resin of the polymer film in the case of one layer.

10. The polymer film according to any one of claims 1 to 9, which is a film for a head-up display in the case of one layer.

11. The polymer film of claim 10 having a thick end and a thin end having a thickness less than said thick end.

12. The polymer film according to any one of claims 1 to 7, which has a three-layer structure in the case of a plurality of layers, the upper and lower layers being protective layers and sandwiching an intermediate layer.

13. The polymer film according to claim 12, wherein the polyvinyl acetal resin of the protective layer has a hydroxyl group content ratio of 27mol% to 31mol%, and/or an acetalization degree of 68mol% to 72mol%.

14. The polymer film according to claim 12, wherein the plasticizer is 30 to 60 parts by weight based on 100 parts by weight of the polyvinyl acetal resin of the protective layer.

15. The polymer film according to claim 12, wherein the polyvinyl acetal resin of the intermediate layer has a hydroxyl group content ratio of 22 to 27mol%, and/or an acetalization degree of 62 to 68mol%.

16. The polymer film according to claim 12, wherein the plasticizer is 60 to 90 parts by weight per 100 parts by weight of the polyvinyl acetal resin of the intermediate layer.

17. The polymer film according to claim 12, which is an intermediate film for laminated glass, having a thickness of 0.5 to 2mm.

18. The polymer film of claim 17 having a thickness of 0.8mm and the protective layer/interlayer/protective layer has a thickness of 0.335mm/0.13mm/0.335mm.