Film for laminated glass, preparation method of film and safe laminated glass

Abstract

The invention discloses a film for laminated glass, a preparation method of the film and safe laminated glass, and relates to the technical field of laminated glass, the film is of an n + 1 layer structure, and n is an integer greater than or equal to 0; when n is equal to 0, the n + 1 layer structure is an A layer structure; when n is greater than 0, the n + 1 layer structure is a multi-layer structure formed by sequentially staggering and overlapping the A layer structure and the B layer structure, and the uppermost layer and the lowermost layer are the A layer structure; the A-layer structure comprises the following components in parts by weight: 100 parts of polyvinyl acetal resin, 30-45 parts of a plasticizer and 0.2-2 parts of an additive; the B-layer structure comprises the following components in parts by weight: 100 parts of polyvinyl acetal resin and 50-90 parts of a plasticizer; the film has the MD direction and the TD direction, is applied to the manufacturing process of the safety laminated glass, and can effectively improve the overflow phenomenon of the film in the MD direction and the TD direction.

Description

Technical Field

[0001] The present invention relates to the technical field of laminated glass, and in particular to a film for laminated glass, a preparation method thereof, and safety laminated glass. Background Art

[0002] Safety laminated glass is a special glass made by sandwiching one or more layers of PVB film between two layers of ordinary glass. When subjected to strong external impact, the PVB film absorbs a large amount of impact energy through a certain degree of elastic bending and deformation. Glass fragments will adhere firmly to the PVB film and will not fly away. The impact object will not easily penetrate the glass, thereby minimizing possible damage.

[0003] There are three main processes for making safety laminated glass: 1. In the construction field, in the production of building safety laminated glass, the laminated glass needs to be pre-pressed and exhausted, the temperature is above 100℃, and it is pressed with clamps. It is then placed in an autoclave and pressurized, heated, and pressure-maintained, and then cooled to make safety glass. The pressure in the autoclave is 0.9-1.3MPa and the temperature is 110-150℃.

[0004] 2. In the photovoltaic field, when manufacturing double-glass photovoltaic modules, the laminated glass of the module is pre-pressed and degassed using a laminator. The lower chamber temperature is 120-180°C, and the upper chamber temperature is 100-130°C for 10-30 minutes. BIPV modules are pressed together in an autoclave, using similar process conditions.

[0005] 3. In the automotive field, when making laminated glass for automobile windshields, side windshields, and automobile sunroofs, after the laminated glass is sampled, it is placed in a vacuum bag or vacuum box for vacuum exhaust. The vacuum degree is between -90 and -100 kPa, and the temperature is raised from room temperature to 130°C (depending on the process). After standing, it is placed in an autoclave. The process conditions are similar to the above-mentioned autoclave process.

[0006] In the above three processes of making laminated glass, sometimes the film will overflow from the edges during the pre-pressing and exhausting stage, especially the edges in the TD direction.

[0007] Currently, in order to address the above situation, efforts are underway to prevent film overflow when using film in the manufacture of laminated glass. Patent CN107428606A discloses an interlayer film for laminated glass having an MD direction and a TD direction. In the MD direction of the interlayer film, the birefringence of the first surface portion is set to ΔnMDA, the birefringence of the second surface portion is set to ΔnMDB, and the birefringence of the central portion is set to ΔnMDC. The film comprises a second surface portion on the other side in the thickness direction, and a central portion between the first and second surface portions. ΔnMDA, ΔnMDB, and ΔnMDC are all below 0.25×10-3. However, the heat treatment time and temperature control of the film significantly affect the refractive index, placing high demands on production efficiency and control.

[0008] However, in actual application, film will still overflow from the edges of laminated glass, especially in the production of automobile windshields and photovoltaic modules. Summary of the Invention

[0009] The purpose of the present invention is to provide a film for laminated glass, a preparation method thereof, and safety laminated glass, to solve the following technical problems:

[0010] How to prevent film from overflowing from the edges of laminated glass.

[0011] The purpose of the present invention can be achieved through the following technical solutions:

[0012] In a first aspect, the present invention discloses a film for laminated glass, wherein the film has an n+1 layer structure, where n is an integer ≥ 0; when n=0, the n+1 layer structure is an A layer structure; when n>0, the n+1 layer structure is a multilayer structure formed by alternating an A layer structure and a B layer structure, with both the top layer and the bottom layer being an A layer structure;

[0013] The A layer structure comprises the following components in parts by weight: 100 parts of polyvinyl acetal resin, 30-45 parts of plasticizer, and 0.2-2 parts of additives;

[0014] The B layer structure comprises the following components in parts by weight: 100 parts of polyvinyl acetal resin and 50-90 parts of plasticizer.

[0015] Furthermore, the B layer structure also includes 0.2-2 parts of additives.

[0016] Furthermore, the hydroxyl content of the polyvinyl acetal resin in the A layer structure is 15-22%, and the hydroxyl content of the polyvinyl acetal resin in the B layer structure is 8-15%.

[0017] Furthermore, the plasticizer is dibutyl phthalate, dioctyl phthalate, triethylene glycol diisooctanoate, tricresyl phosphate, tetraethylene glycol diheptanoate, dibutyl sebacate, dioctyl sebacate, dioctyl adipate; and / or.

[0018] Furthermore, the additives include antioxidants, ultraviolet absorbers, heat insulating agents, adhesion regulators; and / or.

[0019] Preferably, the antioxidant is selected from at least one of a phenolic antioxidant and a phosphite antioxidant; wherein the phenolic antioxidant is selected from one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester, 2-methylenebis(4-methyl-6-tert-butylphenol), and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; and the phosphite antioxidant is selected from one of tris[2,4-di-tert-butylphenyl]phosphite, dioctadecyl alcohol pentaerythritol diphosphite, and bis(3,5-di-tert-butylphenyl)pentaerythritol diphosphite.

[0020] Preferably, the ultraviolet absorber is a benzotriazole ultraviolet absorber, and the benzotriazole ultraviolet absorber is selected from 2-(2ˊ-hydroxy-5ˊ-methyl)-benzotriazole, 2-(2ˊ-hydroxy-3ˊ-tert-butyl-5ˊ-methyl)-5-chloro-benzotriazole, 2-(2ˊ-hydroxy-3ˊ5ˊ-di-tert-butyl)-5-chloro-benzotriazole, 2-(2ˊ-hydroxy-3ˊ5ˊ-di-tert-amyl)-benzotriazole, and 2-(2ˊ-hydroxy-5ˊ-tert-octyl)-benzotriazole.

[0021] Preferably, the heat insulating agent is selected from one or more of a series of tungsten oxide heat insulating agents such as ITO, ZAO, ATO, and GZO. The amount of the heat insulating agent added can be adjusted according to the transmittance and haze requirements of the film.

[0022] Preferably, the adhesion regulator is one or more of alkali metal salts, alkali metal bases, and alkali metal oxides, the alkali metal salt is at least one of potassium formate, potassium acetate, potassium carbonate, potassium bicarbonate, sodium formate, sodium acetate, sodium carbonate and sodium bicarbonate; the alkali metal base is at least one of potassium hydroxide and sodium hydroxide; the alkali metal oxide is at least one of potassium oxide and sodium oxide.

[0023] Furthermore, when the volatile matter of the film is ≤1.0%, the melt index at 150°C is 7-9 times that at 120°C; the melt index at 190°C is 0.9-1.4 times that at 120°C; and the film has an MD direction and a TD direction.

[0024] In a second aspect, the present invention further discloses a method for preparing the film for laminated glass as described above, comprising the following steps:

[0025] Step 1: Place the components of the A layer structure in an extruder according to the weight ratio and plasticize them to obtain a sheet material A; if n=0, proceed directly to step 4; if n>0, proceed to step 2;

[0026] Step 2: Place the components of the B layer structure in an extruder according to the weight ratio and plasticize them to obtain a sheet material B, and then proceed to step 3;

[0027] Step 3: Alternately stack the sheet material A and the sheet material B in a mold to form a fixed film, and then proceed to step 4;

[0028] Step 4: initially cool the temperature of the shaped film to 25°C, then initially heat it to 80-140°C, then cool it to 25°C, and then heat it to 80-140°C, so that the width of the shaped film after heating is more than 1 times that after the initial cooling, thereby obtaining the film.

[0029] Further, after step 4 is completed, proceed to step 5, which is as follows:

[0030] Step 5: Cut 10 cm from each end of the film in the TD direction, and then pull it to the winder for winding and collection. After collection, cut more than 50 cm from the upper end of the film in the MD direction.

[0031] Furthermore, in step 1, the total thickness of the sheet material A is 70-94% of the total thickness of the film, and the thickness of the sheet material B is 6-30% of the total thickness of the film.

[0032] In a third aspect, the present invention further discloses a safety laminated glass comprising a composite structure of two or more pieces of glass, wherein at least one layer of the laminated glass film as described above is disposed between two adjacent pieces of glass.

[0033] Beneficial effects of the present invention:

[0034] The film of the present invention can improve the internal stress of the film during the extrusion plasticization and shaping stages by controlling the film melt index at different temperatures. The temperature of the shaped film is initially cooled to 25°C, then initially heated to 80-140°C, then cooled to 25°C, and then heated to 80-140°C. This allows the width of the shaped film after heating to be more than twice that after the initial cooling, thereby releasing the internal stress of the film and reducing the dimensional change of the film in the MD and TD directions. When applied to the manufacturing process of safety laminated glass, the film can effectively improve the overflow phenomenon of the film in the MD and TD directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] Figure 1 Schematic diagram of the structure of the film in Example 1 of the present invention;

[0037] Figure 2 It is a schematic structural diagram of the safety laminated glass of the present invention. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0040] The raw materials used in the following examples were all purchased from commercial sources, as follows:

[0041] Polyvinyl acetal resin (PVB resin): a product of Anhui Wanwei High-tech Materials Co., Ltd.

[0042] Plasticizer: Triethylene glycol diisooctanoate, a product of Chaohu Wanwei Jinquan Industrial Co., Ltd.

[0043] Alkali metal base: magnesium hydroxide (chemically pure) is used.

[0044] Alkali metal salts: potassium acetate (chemically pure) is used.

[0045] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]

[0046] UV absorber: 2-(2ˊ-hydroxy-3ˊ-tert-butyl-5ˊ-methyl)-5-chloro-benzotriazole;

[0047] Thermal insulation agent: Choose one of the ITO, ATO or GZO series.

[0048] The film products in the following examples and comparative examples are all made as three-layer structure films, with the thickness controlled at 0.76±0.02 mm.

[0049] Example 1

[0050] This embodiment discloses a film for laminated glass, which is prepared in the following steps:

[0051] Step 1: Placing a mixture of 100 parts of polyvinyl acetal resin (hydroxyl content of 17%), 30 parts of plasticizer, and 0.2 parts of additives (alkali metal base, alkali metal salt, antioxidant, and ultraviolet absorber) in an extruder for plasticization according to weight ratio to obtain a sheet material A with a thickness of 0.32 mm;

[0052] Step 2: 100 parts of polyvinyl acetal resin (hydroxyl content: 10%), 50 parts of plasticizer, and 0.2 parts of additives (alkali metal base, alkali metal salt, antioxidant, and ultraviolet absorber) are placed in an extruder for plasticization according to weight ratio to obtain a sheet material B with a thickness of 0.12 mm;

[0053] Step 3: Alternately stack the sheet material A and the sheet material B in a mold and shape them to obtain a shaped film with a thickness of 0.76 mm;

[0054] Step 4: Initially cool the temperature of the shaped film to 25°C, then initially heat it up to 80°C, then cool it down to 25°C, then heat it up to 80°C, so that the width of the shaped film after heating up is more than 1 times that after the initial cooling, and obtain the following Figure 1 Film shown.

[0055] Step 5: Cut 10 cm from each end of the film in the TD direction, and then pull it to the winder for winding and collection. After collection, cut more than 50 cm from the upper end of the film in the MD direction.

[0056] Example 2

[0057] This embodiment discloses a film for laminated glass. Compared with the embodiment 1, the only difference is step 4. Step 4 of this embodiment is as follows:

[0058] Step 4: initially cool the temperature of the shaped film to 25°C, then initially heat it to 100°C, then cool it to 25°C, and then heat it to 100°C, so that the width of the shaped film after heating is more than 1 times that after the initial cooling, to obtain a film.

[0059] The other steps and conditions remained the same, and finally a film for laminated glass was prepared.

[0060] Example 3

[0061] This embodiment discloses a film for laminated glass. Compared with the embodiment 1, the only difference is step 4. Step 4 of this embodiment is as follows:

[0062] Step 4: initially cool the temperature of the shaped film to 25°C, then initially heat it to 120°C, then cool it to 25°C, and then heat it to 120°C, so that the width of the shaped film after heating is more than 1 times that after the initial cooling, to obtain a film.

[0063] The other steps and conditions remained the same, and finally a film for laminated glass was prepared.

[0064] Example 4

[0065] This embodiment discloses a film for laminated glass. Compared with the embodiment 1, the only difference is step 4. Step 4 of this embodiment is as follows:

[0066] Step 4: initially cool the temperature of the shaped film to 25°C, then initially heat it to 140°C, then cool it to 25°C, and then heat it to 140°C, so that the width of the shaped film after heating is more than 1 times that after the initial cooling, to obtain a film.

[0067] The other steps and conditions remained the same, and finally a film for laminated glass was prepared.

[0068] Example 5

[0069] This embodiment discloses a film for laminated glass. Compared with Example 4, the only difference is that the plasticizer in step 1 is replaced with 35 parts, and the other steps and conditions remain the same, and finally a film for laminated glass is prepared.

[0070] Example 6

[0071] This embodiment discloses a film for laminated glass. Compared with Example 4, the only difference is that the plasticizer in step 1 is replaced with 40 parts, and the other steps and conditions remain the same, and finally a film for laminated glass is prepared.

[0072] Example 7

[0073] This embodiment discloses a film for laminated glass. Compared with Example 4, the only difference is that the plasticizer in step 1 is replaced with 45 parts, and the other steps and conditions remain the same, and finally a film for laminated glass is prepared.

[0074] Example 8

[0075] This embodiment discloses a film for laminated glass. Compared with Example 6, the only difference is that the plasticizer in step 2 is replaced with 60 parts, and the other steps and conditions remain the same, and finally a film for laminated glass is prepared.

[0076] Example 9

[0077] This embodiment discloses a film for laminated glass. Compared with Example 6, the only difference is that the plasticizer in step 2 is replaced with 70 parts, and the other steps and conditions remain the same, and finally a film for laminated glass is prepared.

[0078] Example 10

[0079] This embodiment discloses a film for laminated glass. Compared with Example 6, the only difference is that the plasticizer in step 2 is replaced with 80 parts, and the other steps and conditions remain the same, and finally a film for laminated glass is prepared.

[0080] Example 11

[0081] This embodiment discloses a film for laminated glass. Compared with Example 6, the only difference is that the plasticizer in step 2 is replaced with 90 parts, and the other steps and conditions remain the same, and finally a film for laminated glass is prepared.

[0082] Comparative Example 1

[0083] Step 1: Placing a mixture of 100 parts of polyvinyl acetal resin (hydroxyl content of 17%), 25 parts of plasticizer, and 0.2 parts of additives (alkali metal base, alkali metal salt, antioxidant, and ultraviolet absorber) in an extruder for plasticization according to weight ratio to obtain a sheet material A with a thickness of 0.32 mm;

[0084] Step 2: 100 parts of polyvinyl acetal resin (hydroxyl content: 10%), 40 parts of plasticizer, and 0.2 parts of additives (alkali metal base, alkali metal salt, antioxidant, and ultraviolet absorber) are placed in an extruder for plasticization according to weight ratio to obtain a sheet material B with a thickness of 0.12 mm;

[0085] Step 3: Alternately stack the sheet material A and the sheet material B in a mold and shape them to obtain a shaped film with a thickness of 0.76 mm;

[0086] Step 4: Initially cool the shaped film to 25°C, then cut 10 cm from each end of the film in the TD direction, and then pull it to the winder for winding and collection. After collection is completed, cut more than 50 cm from the upper end of the film in the MD direction.

[0087] In order to more intuitively reflect the difference in the amount of raw material components used in Examples 1-11 and Comparative Example 1, the raw material components and weight proportions of the sheet material A and the sheet material B in the films for laminated glass prepared in Examples 1-11 and Comparative Example 1 were statistically analyzed, and the statistical results are listed in Table 1. Table 1 is as follows:

[0088] Table 1 Raw material components and weight parts of flake material A and flake material B

[0089]

[0090] Next, a melt index tester (XRL-400C) was used to test the melt index performance of the films for laminated glass prepared in Examples 1-11 and Comparative Example 1. The test parameters and methods were as follows:

[0091] The sampling mode is "time control", the cutting time is 300s, and the load is 21.6kg; press the "heating" button, and when the temperature displayed on the digital thermometer reaches 120℃, keep the temperature constant for 20-30 minutes; cut the film into sheets within 2mm long and 2mm wide, weigh 5g with an analytical balance, and after the instrument displays "the temperature has been constant, do you want to start the test?", take out the guide sleeve and plunger, and quickly add the stirred sample into the barrel with a funnel (the addition is required to be completed within one minute), add the plunger and guide sleeve, and press firmly; add all the The instrument needs to be loaded. After preheating for four minutes, press the "Test" button and the instrument will automatically start timing testing. Whenever the time display reaches the set value, the material will be cut once and the timing will be restarted. Take three consecutive sections of material, weigh them separately after cooling, and take the average value of the three sections as m. If the relative error of the weighing results of the three sections is ≥10%, the test fails and needs to be retested. Test the film melt index at 120℃ and 150℃, and the melt index meter load is 21.6kg; test the film melt index at 190℃, and the melt index meter load is 2.16kg.

[0092] The results are calculated using the MFR (mass method), specifically:

[0093] MFR (120℃, 21.6kg)=treg×m / t

[0094] Where: MFR (120℃, 21.6kg) - melt mass flow rate value, unit: g / 10min;

[0095] m——average mass of cut material, g;

[0096] treg—reference time (10 min), 600 s;

[0097] t——time interval for cutting, s.

[0098] The valid figures are rounded to two decimal places.

[0099] The melt index at 150°C is recorded as a multiple of the melt index at 120°C, and the melt index at 190°C is recorded as a multiple of the melt index at 120°C. The test structures are then listed in Table 2. Table 2 is as follows:

[0100] Table 2 Melt index of films for laminated glass

[0101]

[0102]

[0103] By analyzing the data in Table 2, it can be seen that the films for laminated glass prepared in Examples 1-11 have a melting index at 150°C that is 7-9 times that of the melting index at 120°C; and a melting index at 190°C that is 0.9-1.4 times that of the melting index at 120°C, while the multiples of Comparative Example 1 are lower than this range.

[0104] The films for laminated glass prepared in Examples 1-11 were respectively applied to laminated glass. The specific method for preparing the laminated glass was as follows: the film was cut into a size of 30 cm*30 cm and placed between two pieces of glass with a thickness of 2 mm. The glass was 30 cm*30 cm in size to prepare the laminated glass. The laminated glass was placed in a vacuum bag and evacuated to maintain a vacuum degree of -(90-100) KPa. The temperature was raised from room temperature to 80°C for not less than 20 minutes, and then cooled to room temperature. The laminated glass was taken out to obtain the following: Figure 2 Laminated glass shown.

[0105] The film dimensions in the MD and TD directions of the laminated glass were measured, and the test results are listed in Table 3. It should be noted that the shrinkage of the film at the end of the laminated glass was evaluated as "-". Table 3 is as follows:

[0106] Table 3 Film dimensions of laminated glass in MD and TD directions

[0107]

[0108]

[0109] By analyzing the data in Table 3, it can be seen that when pre-pressing and exhausting laminated glass, by comparing the laminated glass made using the films for laminated glass prepared in Examples 1-11 with that prepared in Comparative Example 1, the overflow of the film in the MD and TD directions can be significantly improved.

[0110] The above describes in detail several embodiments of the present invention. However, the above contents are only preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A film for laminated glass, characterized in that: The film has an n+1 layer structure, where n is an integer ≥ 0; when n=0, the n+1 layer structure is an A-layer structure; when n>0, the n+1 layer structure is a multilayer structure formed by alternating A-layer structures and B-layer structures, with both the top and bottom layers being A-layer structures; The A layer structure comprises the following components in parts by weight: 100 parts of polyvinyl acetal resin, 30-45 parts of plasticizer, and 0.2-2 parts of additives; The B layer structure comprises the following components in parts by weight: 100 parts of polyvinyl acetal resin and 50-90 parts of plasticizer.

2. The film for laminated glass according to claim 1, characterized in that: The B layer structure further comprises 0.2-2 parts of additives.

3. The film for laminated glass according to claim 1, characterized in that: The hydroxyl content of the polyvinyl acetal resin in the A layer structure is 15-22%, and the hydroxyl content of the polyvinyl acetal resin in the B layer structure is 8-15%.

4. The film for laminated glass according to claim 1, characterized in that: The plasticizer is dibutyl phthalate, dioctyl phthalate, triethylene glycol diisooctanoate, tricresyl phosphate, tetraethylene glycol diheptanoate, dibutyl sebacate, dioctyl sebacate, dioctyl adipate; and / or.

5. The film for laminated glass according to claim 1 or 2, characterized in that: The additives include antioxidants, ultraviolet absorbers, heat shielding agents, adhesion regulators; and / or.

6. The film for laminated glass according to claim 1, characterized in that: When the volatile matter of the film is ≤1.0%, the melt index at 150°C is 7-9 times that at 120°C; the melt index at 190°C is 0.9-1.4 times that at 120°C; and the film has an MD direction and a TD direction.

7. A method for preparing a film for laminated glass according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: Place the components of the A layer structure in an extruder according to the weight ratio and plasticize them to obtain a sheet material A; if n=0, proceed directly to step 4; if n>0, proceed to step 2; Step 2: Place the components of the B layer structure in an extruder according to the weight ratio and plasticize them to obtain a sheet material B, and then proceed to step 3; Step 3: Alternately stack the sheet material A and the sheet material B in a mold to form a fixed film, and then proceed to step 4; Step 4: initially cool the temperature of the shaped film to 25°C, then initially heat it to 80-140°C, then cool it to 25°C, and then heat it to 80-140°C, so that the width of the shaped film after heating is more than 1 times that after the initial cooling, thereby obtaining the film.

8. The method for preparing a film for laminated glass according to claim 7, wherein: After completing step 4, proceed to step 5, as follows: Step 5: Cut 10 cm from each end of the film in the TD direction, and then pull it to the winder for winding and collection. After collection, cut more than 50 cm from the upper end of the film in the MD direction.

9. The method for preparing a film for laminated glass according to claim 7, wherein: In step 1, the total thickness of the sheet material A is 70-94% of the total thickness of the film, and the thickness of the sheet material B is 6-30% of the total thickness of the film.

10. A safety laminated glass, characterized in that: A composite structure comprising two or more pieces of glass, wherein at least one layer of the film for laminated glass according to any one of claims 1 to 6 is arranged between two adjacent pieces of glass.

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