JPH0873244A - Intermediate film for laminated glass - Google Patents

Abstract

PURPOSE: To obtain an intermediate film excellent in transparency, piercing resistance and glass scattering preventing property, giving a laminated glass whose peripheral part is less liable to devitrification or whitening even when it is put in an atmosphere at high humidity and excellent also in extensibility at the time of laminating. CONSTITUTION: A transparent polyolefin resin film having <=0.05mm thickness is held between plasticized polyvinyl butyral resin films and they are stuck together to obtain the objective intermediate film having an at least three- layered structure. A film of low density polyethylene resin produced by a high pressure method or a film of linear low density polyethylene resin is suitable for use as the transparent polyolefin resin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interlayer film for laminated glass having at least a three-layer structure.

[0002]

2. Description of the Related Art Laminated glass in which a plasticized polyvinyl butyral resin film is adhered as an intermediate film between glass plates is excellent in transparency, weather resistance, penetration resistance and glass shatterproof property, and can be used in automobiles, aircrafts and buildings. Widely used for windshields such as.

It is required for this type of laminated glass to further improve the penetration resistance when an impact is applied by improving the intermediate film.

As an interlayer film having improved penetration resistance, a plasticized polyvinyl butyral resin film contains a carboxylic acid metal salt such as potassium acetate or potassium formate as an adhesion modifier (sometimes called an impact strength increasing agent). There is known an intermediate film in which the adhesive force between the glass plate and the intermediate film is adjusted to thereby absorb impact energy more effectively (for example, Japanese Patent Publication No. 42-244).
No. 36).

Further, by sandwiching a cellulose-based thin film or a polyester thin film as a transparent plastic thin film having a weak adhesive force between the plasticized polyvinyl butyral resin film, it is separated from the plasticized polyvinyl butyral resin film when an impact is applied. There is also known an intermediate film which is made to absorb impact energy more effectively by doing so (see, for example, JP-A-56-50147).

[0006]

However, the interlayer film containing the carboxylic acid metal salt has hygroscopicity to the carboxylic acid metal salt, and such a laminated glass is exposed to a harsh environment with a lot of water and humidity. When it is used, there is a problem that moisture gradually penetrates inward from the interface between the glass plate and the intermediate film at the peripheral edge of the laminated glass, and the peripheral portion of the laminated glass is devitrified and whitened. Further, it may be colored during the kneading and forming of the intermediate film.

In the intermediate film having the cellulose-based film or the polyester film sandwiched between them, the cellulose-based film or the transparent polyester film is difficult to stretch, so that the curved shape of the glass plate (for example, the windshield of an automobile is used during the laminating process). When heated and stretched so as to conform to the curved shape), the interlayer film does not follow the stretch of the plasticized polyvinyl butyral resin film, and distortion such as necking occurs in the intermediate film, resulting in poor appearance and poor transparency. There's a problem.

The present invention solves the above problems.
Its purpose is to have excellent transparency, penetration resistance, and glass scattering prevention properties, and even when placed in a high-humidity atmosphere, the peripheral parts of the laminated glass are less likely to devitrify or whiten. An object of the present invention is to provide an interlayer film for laminated glass which is excellent in stretch workability in the case of.

[0009]

[Means for Solving the Problems] The above object is an interlayer film for laminated glass having at least a three-layer structure in which a transparent polyolefin resin film having a thickness of 0.05 mm or less is sandwiched between plasticized polyvinyl butyral resin films. Can be achieved by

The plasticized polyvinyl butyral resin film used in the present invention is obtained by incorporating a plasticizer into polyvinyl butyral resin. The polyvinyl butyral resin is obtained by acetalizing polyvinyl alcohol with n-butyraldehyde, and the polyvinyl butyral resin conventionally used for an interlayer film is used.

In this case, it is preferable to use a polyvinyl alcohol having a saponification degree of 96 mol% or more in order to improve the transparency and heat resistance of the obtained polyvinyl butyral resin. The polyvinyl butyral resin obtained preferably has an acetalization degree of 60 to 70 mol% and an average degree of polymerization of 500 to 3000.

When the average degree of polymerization is less than 500, the mechanical strength of the plasticized polyvinyl butyral resin film is poor, and the penetration resistance of the intermediate film using this resin film is lowered. On the other hand, when the average degree of polymerization exceeds 3000, the melt viscosity of the resin becomes high and it becomes difficult to form a film.

If the degree of acetalization is less than 60 mol%, the resin film obtained will be hard and will not exhibit good elongation, and the compatibility with the plasticizer will decrease and the transparency will deteriorate. On the contrary, when the degree of acetalization exceeds 75 mol%, the resin film obtained becomes too soft, which is not preferable.

As the plasticizer, known plasticizers used for this type of interlayer film, for example, triethylene glycol-di-2-ethylbutyrate, triethylene glycol-di-2-ethylhexoate, Triethylene glycol-di-caprylate, triethylene glycol-di-n-octoate, triethylene glycol-di-n
-Heptoate, tetraethylene glycol-di-n-
Heptate is preferably used.

Such a plasticizer is generally contained in an amount of 20 to 60 parts by weight, preferably 30 to 55 parts by weight, based on 100 parts by weight of the resin.
When the content of the plasticizer is less than 20 parts by weight, it becomes difficult to form a film, and the elongation of the obtained resin film becomes poor. On the contrary, when the content of the plasticizer exceeds 60 parts by weight, the plasticizer bleeds from the obtained resin film and the transparency is deteriorated.

The transparent polyolefin resin film used in the present invention includes high-pressure low-density polyethylene, linear low-density polyethylene, ethylene-propylene random copolymer, and copolymer of α-olefin and 4-methylpentene. A resin film made of a polyolefin resin such as is used.

The film thickness of these transparent polyolefin resin films must be 0.05 mm or less. If this film thickness exceeds 0.05 mm, the transparency of the obtained intermediate film is lowered and it is not suitable as an intermediate film. Particularly, considering the difference in adhesiveness with the plasticized polyvinyl butyral resin film and the tensile elastic modulus, high-pressure low-density polyethylene or linear low-density polyethylene is preferable.

In the present invention, between the plasticized polyvinyl butyral resin film (PVB film), the film thickness of 0.
A transparent polyolefin resin film (PO film) having a thickness of 05 mm or less is sandwiched to form an interlayer film for laminated glass having at least a three-layer structure.

Examples of the structure of such an interlayer film for laminated glass include (1) PVB film / PO film / PVB film,
(2) PVB film / PO film / PVB film / PO film / PVB
Membrane, (3) PVB membrane / PO membrane / PVB membrane / PO membrane / PV
Examples include B film / PO film / PVB film, and the outermost layer is, of course, a plasticized polyvinyl butyral resin film (PV
B film).

The total thickness of the interlayer film for laminated glass is generally in the range of 0.2 to 1.6 mm, particularly 0.4 to 1.2 mm.
Is preferred. If the total film thickness is less than 0.2 mm, the penetration resistance is insufficient, and conversely, if the total film thickness exceeds 1.6 mm, the transparency is lowered and the cost is increased.

Such an interlayer film for laminated glass is generally prepared by separately preparing a plasticized polyvinyl butyral resin film and a transparent polyolefin resin film by an extrusion molding method or a calendar molding method, and laminating them by thermocompression bonding. Although it can be obtained by integration, it can also be obtained by lamination and integration by a multilayer extrusion molding method.

It can also be obtained by sandwiching a plasticized polyvinyl butyral resin film and a transparent polyolefin resin film between glass plates and thermocompressing them to laminate them together during the production of laminated glass.

The plasticized polyvinyl butyral resin film and the transparent polyolefin resin film may be mixed with known additives such as antioxidants and ultraviolet absorbers, if necessary.

The antioxidants include, for example, t-butylhydroxytoluene (BHT), phenolic compounds represented by "Irganox 1010" manufactured by Ciba-Geigy, "LA-57" manufactured by ADEKA ARGUS and the like. The hindered amine type is used.

Examples of the ultraviolet absorber include benzotriazole compounds represented by "Tinuvin P", "Tinuvin 320", "Tinuvin 326" manufactured by Ciba-Geigy, and the like.
A hindered amine system represented by "LA-57" manufactured by ADEKA ARGUS CORPORATION is exemplified.

The interlayer film for laminated glass of the present invention is constructed as described above, and a method similar to the conventional method is employed to manufacture laminated glass using the interlayer film for laminated glass.

For example, a method of sandwiching the above intermediate film between transparent glass plates such as float glass, placing it in a vacuum bag for deaeration, and then transferring to an oven in a deaerated state for thermocompression bonding, or the above deaeration. The laminated glass is manufactured by a method such as thermocompression bonding by a press later.

[0028]

In the interlayer film for laminated glass of the present invention, since the outermost layer is the plasticized polyvinyl butyral resin film, it has excellent adhesiveness to glass and transparency, thereby preventing scattering of glass fragments. In addition, since the plasticized polyvinyl butyral resin film does not contain the metal carboxylate of the prior art, it is difficult to absorb moisture and has excellent moisture resistance, which results in devitrification or whitening of the intermediate film at the peripheral portion of the laminated glass. To be prevented.

Further, a transparent plastic film having a thickness of 0.05 mm is formed between the plasticized polyvinyl butyral resin films.
The following transparent polyolefin resin film is interposed, and the adhesive force between this transparent plastic film and the plasticized polyvinyl butyral resin film is weaker than the adhesive force between the glass plate and the plasticized polyvinyl butyral resin film, and shock is applied. When this occurs, separation or displacement occurs from the interface of the plasticized polyvinyl butyral resin film, which absorbs impact energy and improves penetration resistance.

Moreover, this transparent polyolefin resin film has the property of being easily stretched as compared with the conventional transparent cellulose-based film or transparent polyester film. Incidentally, the plasticized polyvinyl butyral resin film is about 30 kgf / cm ² , the high-pressure polyethylene resin film is about 50 kgf / cm ² , and the linear low-density polyethylene resin film is about 100 kgf / cm ^2.
And the cellulose film and the polyester film show a tensile elastic modulus of about 10,000 kgf / cm ² or more.

Therefore, when the intermediate film of the present invention is used and heated and stretched so as to match the curved shape of the glass plate (for example, the curved shape of the windshield of an automobile), a plasticized polyvinyl butyral resin film is obtained. It follows well and is excellent in extension workability, which prevents the occurrence of distortion such as necking in the intermediate film during the production of laminated glass, and does not cause poor appearance or decrease in transparency.

[0032]

EXAMPLES The advantages of the interlayer film for laminated glass of the present invention will be shown below with reference to Examples and Comparative Examples. Example 1 Preparation of plasticized polyvinyl butyral resin film Polyvinyl butyral resin obtained by acetalizing polyvinyl alcohol having a saponification degree of 99.2 mol% with n-butyraldehyde (average degree of polymerization 1700, degree of acetalization 66.3 mol%). ) 100 parts by weight, 40 parts by weight of a plasticizer (triethylene glycol-di-2-ethylbutyrate), 0.2 parts by weight of an antioxidant (BHT), 0.2 parts by weight of an ultraviolet absorber (Tinuvin P) Compound.

This mixture was melt-kneaded by a roll mill at 150 ° C., and this was kneaded by a press molding machine at 150 ° C. × 120 k.
Press for 30 minutes under the condition of g / cm ² and thickness of 0.25mm
To obtain a transparent plasticized polyvinyl butyral resin film. Then, this sheet was placed in a constant temperature and humidity chamber to have a water content of 0.3 to 0.
It was adjusted to be 6% by weight.

Preparation of transparent polyolefin resin film 100 parts by weight of a high-pressure low-density polyethylene resin (Petrosene 173: manufactured by Tosoh Corporation) was mixed with an antioxidant (BHT) of 0.
1 part by weight and 0.3 part by weight of an ultraviolet absorber (Tinuvin P) are mixed.

This mixture was melt-kneaded by a roll mill at 150 ° C., and this was kneaded by a press molding machine at 130 ° C. × 120 k.
Press for 30 minutes under the condition of g / cm ² and thickness is 0.02mm
To obtain a transparent polyolefin resin film.

Of the interlayer film for laminated glass and laminated glass
Production Using the plasticized polyvinyl butyral resin film (PVB film) and the polyolefin resin film (PE film), PVB film /
An interlayer film for laminated glass is prepared by laminating five layers with a layer structure of PE film / PVB film / PE film / PVB film, and this interlayer film is made of float glass of thickness 2.5 mm × length 300 mm × width 300 mm. Sandwiched between

This sandwich was placed in a vacuum bag and deaerated for 20 minutes at a vacuum degree of 20 torr, then transferred to an oven in the deaerated state and kept at 90 ° C. for 30 minutes. Then, thermocompression bonding was performed in an autoclave under the conditions of 135 ° C. × 12 kg / cm ² to obtain a laminated glass.

Example 2 A polyvinyl butyral resin having an average polymerization degree of 1700 and an acetalization degree of 71.0 mol% was used, and the compounding amount of the plasticizer was 3
A laminated glass was obtained in the same manner as in Example 1 except that the amount was changed to 0 part by weight.

Example 3 A polyvinyl butyral resin having an average degree of polymerization of 1700 and an acetalization degree of 61.5 mol% was used, and the compounding amount of the plasticizer was 5
A laminated glass was obtained in the same manner as in Example 1 except that the amount was changed to 0 part by weight.

Example 4 A laminated glass was obtained in the same manner as in Example 1 except that the thickness of the transparent polyolefin resin film was changed to 0.05 mm.

Example 5 The thickness of the plasticized polyvinyl butyral resin film is 0.20 mm.
And change the thickness of the transparent polyolefin resin film to 0.01
Change to mm, PVB film / PE film / PVB film / PE film / P
A laminated glass was obtained in the same manner as in Example 1 except that the laminated glass was laminated in 7 layers of VB film / PE film / PVB film.

Comparative Example 1 The thickness of the plasticized polyvinyl butyral resin film was 0.75 mm.
Except that the transparent polyolefin resin film was not used and only one layer of this plasticized polyvinyl butyral resin film was used, a laminated glass was obtained in the same manner as in Example 1.

Comparative Example 2 A polyvinyl butyral resin having an average polymerization degree of 1700 and an acetalization degree of 81.5 mol% was used, and the compounding amount of the plasticizer was 2
A laminated glass was obtained in the same manner as in Example 1 except that the amount was changed to 0 part by weight.

Comparative Example 3 A laminated glass was obtained in the same manner as in Example 1 except that the compounding amount of the plasticizer was changed to 70 parts by weight. Comparative Example 4 A laminated glass was obtained in the same manner as in Example 1 except that the thickness of the transparent polyolefin resin film was changed to 0.1 mm.

Comparative Example 5 In the blending of a plasticized polyvinyl butyral resin film, 0.04 parts by weight of potassium acetate (corresponding to an alkalinity titer of 20) was additionally blended to give a plasticized polyvinyl butyral having a thickness of 0.75 mm. A laminated glass was obtained in the same manner as in Example 1 except that a resin film was prepared and only one layer of this plasticized polyvinyl butyral resin film was used without using the transparent polyolefin resin film.

Comparative Example 6 The procedure of Example 1 was repeated, except that the transparent polyolefin resin film having a thickness of 0.02 mm was changed to a transparent cellulose film having a thickness of 0.05 mm (ACECHI 32: manufactured by Daicel Chemical Industries, Ltd.). To obtain laminated glass.

The penetration resistance, transparency, moisture resistance, and extension workability in the laminating process of the interlayer films for laminated glass obtained in each of the above Examples and Comparative Examples were evaluated by the following methods. The results are summarized in Tables 1 and 2.

[0048]

[Table 1]

[0049]

[Table 2]

<Penetration resistance> The laminated glass is held horizontally on a supporting frame, and 2.26 kg of hard spheres are naturally dropped from the upper part of the laminated glass to the center portion at a temperature of 20 ° C. Repeated tests were carried out while gradually increasing the height of the falling ball of the hard sphere, and the height of the falling ball was measured when 50% of the number of tests did not penetrate.

<Transparency> The haze of the laminated glass was measured using a haze meter (integral turbidity meter: manufactured by Tokyo Denshoku Co., Ltd.). <Moisture resistance> Laminated glass at 50 ± 3 ° C, relative humidity 95 ±
It was left at 3% for 2 weeks, and then the distance of the whitened portion (whitening distance) was measured from the peripheral edge of the laminated glass.

<Extension Workability> An interlayer film for laminated glass was cut into a size of 50 mm in length × 50 mm in width to prepare a test piece, which was held at 80 ° C. for 5 minutes, and then a tensile tester (Tensilon UCT -500: manufactured by Orientec Co., Ltd.) and stretched twice at a pulling speed of 100 mm / min. This stretched state was maintained at room temperature for 5 minutes, and the total light transmittance of this test piece was measured with a haze meter (integral turbidity meter: manufactured by Tokyo Denshoku Co., Ltd.), and the state of the test piece was visually observed.

[0053]

As described above, the interlayer film for laminated glass of the present invention has at least a three-layer structure in which a transparent polyolefin resin film having a thickness of 0.05 mm or less is sandwiched between plasticized polyvinyl butyral resin films. It is an interlayer film, which makes it excellent in transparency, penetration resistance, and glass scattering resistance, and even when placed in a high-humidity atmosphere, the periphery of the laminated glass is less likely to devitrify or whiten. It is possible to obtain an intermediate film which is excellent in extension workability during processing.

Therefore, the interlayer film for laminated glass of the present invention is preferably used for windshields of automobiles, aircrafts, buildings, etc., and particularly, for example, in the case of automobile windshields, the interlayer film has a curved shape. When it is used after being stretch-processed, it has an advantage that distortion such as necking is prevented from occurring in the intermediate film, and the appearance defect and the transparency are not deteriorated.

Claims (1)

[Claims] 1. An intermediate film for laminated glass having at least a three-layer structure comprising a transparent polyolefin resin film having a thickness of 0.05 mm or less sandwiched between plasticized polyvinyl butyral resin films.