JP2019147711A - Manufacturing method of interlayer for glass laminate - Google Patents

Abstract

To provide a manufacturing method of an interlayer for glass laminate, capable of adding uniform unevenness to a surface by an extrusion lip embossment method using melt fracture.SOLUTION: There is provided a manufacturing method of an interlayer for glass laminate having many unevenness on at least one surface, having a process for preparing a raw material resin composition so that melting viscosity at extrusion temperature is 2.5×10Pa s, and a process for adding many unevenness to at least one surface of the interlayer for glass laminate by an extrusion lip embossment method using melt fracture.SELECTED DRAWING: None

Description

The present invention relates to a method for producing an interlayer film for laminated glass capable of imparting uniform irregularities to a surface by an extrusion lip embossing method using a melt fracture.

Laminated glass obtained by sandwiching an interlayer film for laminated glass containing plasticized polyvinyl butyral between two glass plates and bonding them together is widely used particularly as a vehicle windshield.

In the method for producing laminated glass, for example, a laminated glass obtained by cutting an interlayer film for laminated glass unwound from a roll into an appropriate size and sandwiching the interlayer film for laminated glass between at least two glass plates. The body is put into a rubber bag and sucked under reduced pressure, and preliminarily pressure-bonded while deaerating air remaining between the glass plate and the intermediate film. Next, for example, a method of performing main pressure bonding by heating and pressing in an autoclave is performed (for example, Patent Document 1).

In the laminated glass manufacturing process, deaeration at the time of laminating the glass and the interlayer film for laminated glass in the pre-bonding process is important. For this reason, many unevenness | corrugations are formed in the at least one surface of the intermediate film for laminated glasses in order to ensure the deaeration at the time of laminated glass manufacture.
As a method for forming such irregularities, an extrusion lip embossing method using melt fracture has recently been performed (for example, Patent Document 2).
However, the interlayer film for laminated glass produced by the extrusion lip embossing method using a melt fracture has a problem that unevenness formed on the surface is uneven.

JP-A-8-26789 Special table 2010-523379

An object of this invention is to provide the manufacturing method of the intermediate film for laminated glasses which can provide a uniform unevenness | corrugation on the surface by the extrusion lip embossing method using a melt fracture in view of the said present condition.

The present invention is a method for producing an interlayer film for laminated glass having a large number of irregularities on at least one surface, wherein the raw resin composition is such that the melt viscosity at the extrusion temperature is 2.5 × 10 ⁴ Pa · s or more. A method for producing an interlayer film for laminated glass, comprising a step of preparing a product and a step of imparting a number of irregularities to at least one surface of the interlayer film for laminated glass by an extrusion lip embossing method using a melt fracture.
The present invention is described in detail below.

The present inventors examined the cause of unevenness of the irregularities formed on the surface of the interlayer film for laminated glass produced by the extrusion lip embossing method using melt fracture. As a result, it was found that the normal interlayer film for laminated glass was caused by the softness of the raw material resin composition at the extrusion temperature when heated and extruded.
Melt fracture is a phenomenon in which the surface of a formed product undulates when shear stress at a mold exit exceeds a certain critical value when the resin is melted and extruded from a mold. By controlling this melt fracture, irregularities can be imparted to the surface of the interlayer film for laminated glass. Here, it was considered that when the raw material resin composition was soft at the extrusion temperature, surface undulations due to shear stress were non-uniform, and the unevenness imparted was also non-uniform.
As a result of further intensive studies, the present inventors prepared a raw material resin composition so that the melt viscosity at the extrusion temperature was 2.5 × 10 ⁴ Pa · s or more, and this was extruded lip embossing using a melt fracture. By providing the method, it was found that extremely uniform irregularities could be imparted, and the present invention was completed.

The method for producing an interlayer film for laminated glass of the present invention includes a step of preparing a raw material resin composition so that a melt viscosity at an extrusion temperature is 2.5 × 10 ⁴ Pa · s or more. By setting the melt viscosity at the extrusion temperature to 2.5 × 10 ⁴ Pa · s or more, an interlayer film for laminated glass having extremely uniform irregularities can be obtained by an extrusion lip embossing method using a melt fracture.
In the extrusion lip embossing method using melt fracture, the extrusion temperature (the temperature of the resin at the die entrance) is set to about 160 to 250 ° C. Therefore, in this step, the raw material resin composition is prepared so that the melt viscosity at 160 to 250 ° C. is 2.5 × 10 ⁴ Pa · s or more.
The melt viscosity is specified in JIS K7244-10, and is measured mainly at a frequency of 1 hertz using a rheometric mechanical spectrometer.

The interlayer film for laminated glass produced by the method for producing an interlayer film for laminated glass of the present invention may have a single layer structure composed of one kind of resin film or a multilayer structure in which two or more kinds of resin films are laminated. May be. When the interlayer film for laminated glass has a multilayer structure, at least the raw material resin composition of the resin film constituting the outermost layer is prepared so that the melt viscosity at the extrusion temperature is 2.5 × 10 ⁴ Pa · s or more. To do.

The raw material resin composition preferably contains a thermoplastic resin.
Examples of the thermoplastic resin include polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, polytrifluoride ethylene, and acrylonitrile-butadiene-styrene copolymer. Examples thereof include polyester, polyether, polyamide, polycarbonate, polyacrylate, polymethacrylate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyvinyl acetal, and ethylene-vinyl acetate copolymer. Especially, it is preferable that the said resin layer contains a polyvinyl acetal or an ethylene-vinyl acetate copolymer, and it is more preferable to contain a polyvinyl acetal.

The polyvinyl acetal can be produced, for example, by acetalizing polyvinyl alcohol with an aldehyde. The polyvinyl alcohol can be produced, for example, by saponifying polyvinyl acetate. The saponification degree of the polyvinyl alcohol is generally in the range of 70 to 99.8 mol%.

The average degree of polymerization of the polyvinyl alcohol is preferably 200 or more, more preferably 500 or more, further preferably 1700 or more, particularly preferably more than 1700, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, Particularly preferably, it is less than 3000. When the average degree of polymerization is not less than the above lower limit, the penetration resistance of the laminated glass is further enhanced. When the average degree of polymerization is not more than the above upper limit, the intermediate film can be easily molded.
The average degree of polymerization of the polyvinyl alcohol is determined by a method based on JIS K6726 “Testing method for polyvinyl alcohol”.

The number of carbon atoms of the acetal group contained in the polyvinyl acetal is not particularly limited. The aldehyde used when manufacturing the said polyvinyl acetal is not specifically limited. The preferable lower limit of the carbon number of the acetal group in the polyvinyl acetal is 3, and the preferable upper limit is 6. When the carbon number of the acetal group in the polyvinyl acetal is 3 or more, the glass transition temperature of the intermediate film is sufficiently low, and bleeding out of the plasticizer can be prevented. By setting the number of carbon atoms in the aldehyde to 6 or less, synthesis of polyvinyl acetal can be facilitated and productivity can be secured. The aldehyde having 3 to 6 carbon atoms may be a linear aldehyde or a branched aldehyde, and examples thereof include n-butyraldehyde and n-valeraldehyde. .

The aldehyde is not particularly limited. In general, an aldehyde having 1 to 10 carbon atoms is preferably used as the aldehyde. Examples of the aldehyde having 1 to 10 carbon atoms include propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, and 2-ethylbutyraldehyde. Moreover, n-hexyl aldehyde, n-octyl aldehyde, n-nonyl aldehyde, n-decyl aldehyde, formaldehyde, acetaldehyde, benzaldehyde, etc. are mentioned, for example. Of these, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-hexylaldehyde or n-valeraldehyde is preferable, propionaldehyde, n-butyraldehyde or isobutyraldehyde is more preferable, and n-butyraldehyde is still more preferable. As for the said aldehyde, only 1 type may be used and 2 or more types may be used together.

The hydroxyl group content (hydroxyl group amount) of the polyvinyl acetal is preferably 10 mol% or more, more preferably 15 mol% or more, still more preferably 18 mol% or more, preferably 40 mol% or less, more preferably 35 mol%. It is as follows. When the hydroxyl group content is at least the above lower limit, the adhesive strength of the interlayer film is further increased. Further, when the hydroxyl group content is not more than the above upper limit, the flexibility of the interlayer film is increased, and the handling of the interlayer film is facilitated.
The content ratio of the hydroxyl group of the polyvinyl acetal is a value obtained by dividing the amount of ethylene group to which the hydroxyl group is bonded by the total amount of ethylene group of the main chain, as a percentage. The amount of ethylene group to which the hydroxyl group is bonded can be determined, for example, by measuring in accordance with JIS K6726 “Testing method for polyvinyl alcohol” or in accordance with ASTM D1396-92.

The degree of acetylation (acetyl group amount) of the polyvinyl acetal is preferably 0.1 mol% or more, more preferably 0.3 mol% or more, still more preferably 0.5 mol% or more, preferably 30 mol% or less. More preferably, it is 25 mol% or less, More preferably, it is 20 mol% or less. When the acetylation degree is not less than the above lower limit, the compatibility between the polyvinyl acetal and the plasticizer is increased. When the acetylation degree is not more than the above upper limit, the moisture resistance of the interlayer film and the laminated glass is increased.
The degree of acetylation is obtained by subtracting the amount of ethylene groups to which acetal groups are bonded and the amount of ethylene groups to which hydroxyl groups are bonded from the total amount of ethylene groups of the main chain, It is a value indicating the mole fraction obtained by dividing by the percentage. The amount of ethylene group to which the acetal group is bonded can be measured, for example, according to JIS K6728 “Testing methods for polyvinyl butyral” or according to ASTM D1396-92.

The degree of acetalization of the polyvinyl acetal (in the case of polyvinyl butyral resin, the degree of butyralization) is preferably 50 mol% or more, more preferably 53 mol% or more, still more preferably 60 mol% or more, and particularly preferably 63 mol%. As mentioned above, Preferably it is 85 mol% or less, More preferably, it is 75 mol% or less, More preferably, it is 70 mol% or less. When the degree of acetalization is not less than the above lower limit, the compatibility between the polyvinyl acetal and the plasticizer increases. When the degree of acetalization is not more than the above upper limit, the reaction time required for producing polyvinyl acetal is shortened.
The degree of acetalization is a value indicating the mole fraction obtained by dividing the amount of ethylene groups to which acetal groups are bonded by the total amount of ethylene groups in the main chain, as a percentage.
The degree of acetalization was determined by measuring the degree of acetylation and the hydroxyl group content by a method based on JIS K6728 “Testing methods for polyvinyl butyral” or a method based on ASTM D1396-92. The rate can be calculated and then calculated by subtracting the degree of acetylation and the hydroxyl content from 100 mol%.

The hydroxyl group content (hydroxyl group amount), acetalization degree (butyralization degree), and acetylation degree are preferably calculated from results measured by a method based on JIS K6728 “Testing methods for polyvinyl butyral”. When the polyvinyl acetal is a polyvinyl butyral resin, the hydroxyl group content (hydroxyl content), the degree of acetalization (degree of butyralization) and the degree of acetylation are measured by a method according to JIS K6728 “Testing methods for polyvinyl butyral”. It is preferable to calculate from the results.

The raw material resin composition preferably contains a plasticizer.
The plasticizer is not particularly limited as long as it is a plasticizer generally used for an interlayer film for laminated glass. For example, organic plasticizers such as monobasic organic acid esters and polybasic organic acid esters, organic Examples thereof include phosphoric acid plasticizers such as phosphoric acid compounds and organic phosphorous acid compounds.
Examples of the organic plasticizer include triethylene glycol-di-2-ethylhexanoate, triethylene glycol-di-2-ethylbutyrate, triethylene glycol-di-n-heptanoate, and the like. Further, tetraethylene glycol-di-2-ethylhexanoate, tetraethylene glycol-di-2-ethylbutyrate, tetraethylene glycol-di-n-heptanoate and the like can be mentioned. Further, diethylene glycol-di-2-ethylhexanoate, diethylene glycol-di-2-ethylbutyrate, diethylene glycol-di-n-heptanoate and the like can be mentioned. Among these, the resin layer preferably contains triethylene glycol-di-2-ethylhexanoate, triethylene glycol-di-2-ethylbutyrate, or triethylene glycol-di-n-heptanoate. More preferably, it contains ethylene glycol-di-2-ethylhexanoate.

Although content of the said plasticizer is not specifically limited, The preferable minimum with respect to 100 mass parts of said thermoplastic resins is 25 weight part, and a preferable upper limit is 80 weight part. High penetration resistance can be exhibited as content of the said plasticizer exists in this range. The minimum with more preferable content of the said plasticizer is 30 weight part, and a more preferable upper limit is 70 weight part.

The raw material resin composition preferably contains an adhesive strength modifier. In particular, when the interlayer film for laminated glass has a multilayer structure, the raw material resin composition that is the raw material for the outermost resin film that comes into contact with the glass preferably contains the above-mentioned adhesive force regulator.
As said adhesive force regulator, an alkali metal salt or alkaline-earth metal salt is used suitably, for example. As said adhesive force regulator, salts, such as potassium, sodium, magnesium, are mentioned, for example.
Examples of the acid constituting the salt include organic acids of carboxylic acids such as octylic acid, hexylic acid, 2-ethylbutyric acid, butyric acid, acetic acid, formic acid, and inorganic acids such as hydrochloric acid and nitric acid. Since the adhesive force of glass and a resin layer can be prepared easily when manufacturing a laminated glass, it is preferable that the resin layer which contacts glass contains a magnesium salt as an adhesive force regulator.

The raw material resin composition may contain additives such as antioxidants, light stabilizers, modified silicone oils as flame retardants, flame retardants, antistatic agents, anti-humidants, heat ray reflectors, heat ray absorbers as necessary. It may contain.

Examples of the method of setting the melt viscosity at the extrusion temperature of the raw material resin composition to 2.5 × 10 ⁴ Pa · s or more include a method of blending particulate substances such as pigments, inorganic fillers, and organic fillers. Among these, pigments are preferable because an interlayer film for colored laminated glass can be obtained.

The pigment is not particularly limited. For example, calcium carbonate, barium sulfate, alumina white, silica, white carbon, titanium dioxide, zinc white, carbon black, iron black, zinc phosphate, calcium phosphate, aluminum phosphomolybdate, bismuth oxide. Bismuth hydroxide, bismuth nitrate, bismuth silicate, and the like. Also, for example, hydrotalcite, mica-like iron oxide, perylene black, molybdenum red, bengara, cerium sulfide, yellow iron oxide, ocher, bismuth yellow, zinc sulfide, phthalocyanine blue, phthalocyanine green, aluminum powder, copper powder, brass powder , Stainless steel powder, silver particles, anatase-type titanium oxide, iron oxide, conductive metal powder, and the like. Of these, phthalocyanine blue and phthalocyanine green are preferred because they have high affinity with the thermoplastic resin and are difficult to bleed out.

The shape of the particulate material is not particularly limited, and any shape such as a spherical shape or an indefinite shape can be used.
The size of the particulate material is not particularly limited, but a preferable lower limit of the average particle diameter is 1 μm, and a preferable upper limit is 100 μm. When the average particle diameter of the particulate material is within this range, the melt viscosity at the extrusion temperature of the raw material resin composition can be easily adjusted to 2.5 × 10 ⁴ Pa · s or more. The more preferable lower limit of the average particle diameter of the particulate material is 10 μm, and the more preferable upper limit is 50 μm.

The content of the particulate material in the raw material composition is not particularly limited, but a preferable lower limit with respect to 100 parts by weight of the thermoplastic resin is 0.01 part by weight, and a preferable upper limit is 10 parts by weight. When the content of the particulate matter is within this range, the melt viscosity at the extrusion temperature of the raw material resin composition can easily be 2.5 × 10 ⁴ Pa · s or more. The more preferable lower limit of the content of the particulate matter is 0.1 parts by weight, the more preferable upper limit is 5 parts by weight, the still more preferable lower limit is 0.5 parts by weight, and the still more preferable upper limit is 2 parts by weight.

In the method for producing an interlayer film for laminated glass according to the present invention, a step of imparting a large number of irregularities to at least one surface of the interlayer film for laminated glass is then performed by an extrusion lip embossing method using a melt fracture.
Melt fracture is a phenomenon in which the surface of a formed product undulates when shear stress at a mold exit exceeds a certain critical value when the resin is melted and extruded from a mold. When the melt viscosity at the extrusion temperature of the raw material resin composition is 2.5 × 10 ⁴ Pa · s or more, the surface undulations due to shear stress become uniform, so that the surface is uniformly uneven. An interlayer film for glass can be obtained.

As the extrusion lip embossing method using melt fracture, a conventionally known method can be employed.
In the extrusion lip embossing method using melt fracture, the shape of the unevenness imparted to the surface of the interlayer film for laminated glass is the resin pressure at the die entrance, the resin temperature, the mold temperature, the mold exit width, the mold It is adjusted by controlling the amount of extrusion per width of the mold exit. Further, it is adjusted by controlling the film surface temperature immediately after being discharged from the mold outlet, the distance from the mold outlet to the cooling water tank, the water temperature in the cooling water tank, and the like. For example, when the temperature of the resin or the temperature of the mold is increased, the height of the unevenness to be applied is reduced, and when the width of the exit of the mold is decreased, the average interval of the unevenness to be applied is decreased. The temperature of the resin refers to the temperature of the resin at the mold entrance. In addition, increase the resin pressure at the die inlet, increase the amount of extrusion per width of the die outlet, increase the film surface temperature immediately after being discharged from the die outlet, distance from the die outlet to the cooling water tank The height of the unevenness can be lowered by a method such as increasing the temperature or increasing the water temperature in the cooling water tank. On the contrary, the average interval of the unevenness increases the resin pressure at the die inlet, increases the extrusion amount per width of the mold outlet, increases the film surface temperature immediately after being discharged from the mold outlet, from the mold outlet The distance can be increased by increasing the distance to the cooling water tank or raising the water temperature in the cooling water tank.

More specifically, for example, the resin pressure at the die entrance is 40 to 150 kgf / cm ² , the resin temperature is 160 to 250 ° C., the mold temperature is 100 to 270 ° C., the mold exit width is 700 to 3500 mm, The extrusion amount per width of the mold outlet is adjusted to 130 to 1700 kg / hr · m. Further, the film surface temperature immediately after being discharged from the mold outlet is adjusted to 170 to 250 ° C., the distance from the mold outlet to the cooling water tank is adjusted to 10 to 400 mm, and the water temperature in the cooling water tank is adjusted to the range of 10 to 70 ° C. By this, the unevenness | corrugation which can exhibit sufficient deaeration in the manufacturing process of a laminated glass can be provided.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the intermediate film for laminated glasses which can provide a uniform unevenness | corrugation on the surface by the extrusion lip embossing method using a melt fracture can be provided.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(1) Preparation of raw material resin composition For 100 parts by mass of polyvinyl butyral, 40 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO) as a plasticizer and copper phthalocyanine (PB-15: 3 as a pigment) 1 part by weight of Dainichi Seika Kogyo Co., Ltd.) was added and kneaded thoroughly with a mixing roll to obtain a raw material resin composition.
The polyvinyl butyral was obtained by acetalizing polyvinyl alcohol having an average degree of polymerization of 1700 with n-butyraldehyde, having an acetyl group amount of 1 mol%, a butyral group amount of 69 mol%, and a hydroxyl group amount of 30 mol%. Polyvinyl butyral.
The raw material resin composition is specified in JIS K7244-10, and the complex shear viscosity is mainly measured at a frequency of 1 Hz using a rheometric mechanical spectrometer, and the melt viscosity at an extrusion temperature (170 ° C.) is measured. As a result, it was 3.0 × 10 ⁴ Pa · s.

(2) Production of interlayer film for laminated glass The obtained raw material resin composition was extruded using an extruder to produce an interlayer film for laminated glass. By setting the conditions at the time of extrusion to the following conditions, an interlayer film for laminated glass was formed at the same time by the extrusion lip embossing method using melt fracture.
That is, in the extrusion lip embossing method using melt fracture, the resin pressure at the die entrance is 70 kgf / cm ² , the temperature of the resin composition at the die entrance is 200 ° C., the die temperature is 210 ° C., and the die outlet The width was 1000 mm, and the amount of extrusion per width of the mold outlet was 300 kg / hr · m. Furthermore, the film surface temperature immediately after being discharged from the mold outlet is 200 ° C., the distance from the mold outlet to the cooling water tank is 170 mm, and the water temperature in the cooling water tank is 10 to 20 ° C. At the same time as the formation of the intermediate film, concave and convex shapes were imparted to both sides thereof.
The thickness of the obtained interlayer film for laminated glass was 800 μm.

(Example 2)
For 100 parts by mass of polyvinyl butyral, 40 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO) as a plasticizer and copper phthalocyanine (PB-15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.) as a pigment A raw material resin composition was obtained in the same manner as in Example 1 except that 2 parts by weight were added and kneaded sufficiently with a mixing roll to obtain a raw material resin composition. Further, an interlayer film for laminated glass was produced in the same manner as in Example 1.
The polyvinyl butyral was obtained by acetalizing polyvinyl alcohol having an average degree of polymerization of 3000 with n-butyraldehyde and having an acetyl group amount of 1 mol%, a butyral group amount of 69 mol%, and a hydroxyl group amount of 30 mol%. Polyvinyl butyral.
The raw material resin composition is specified in JIS K7244-10, and the complex shear viscosity is mainly measured at a frequency of 1 Hz using a rheometric mechanical spectrometer, and the melt viscosity at an extrusion temperature (170 ° C.) is measured. As a result, it was 3.5 × 10 ⁴ Pa · s.

(Comparative Example 1)
For 100 parts by mass of polyvinyl butyral, 40 parts by mass of triethylene glycol-di-2-ethylhexanoate (3GO) as a plasticizer and copper phthalocyanine (PB-15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.) as a pigment A raw material resin composition was obtained in the same manner as in Example 1 except that 0.001 part by weight was added and kneaded sufficiently with a mixing roll to obtain a raw material resin composition. Further, an interlayer film for laminated glass was produced in the same manner as in Example 1.
The polyvinyl butyral was obtained by acetalizing polyvinyl alcohol having an average degree of polymerization of 1700 with n-butyraldehyde, having an acetyl group amount of 1 mol%, a butyral group amount of 69 mol%, and a hydroxyl group amount of 30 mol%. Polyvinyl butyral.
The raw material resin composition is specified in JIS K7244-10, and the complex shear viscosity is mainly measured at a frequency of 1 Hz using a rheometric mechanical spectrometer, and the melt viscosity at an extrusion temperature (170 ° C.) is measured. As a result, it was 2.0 × 10 ⁴ Pa · s.

(Evaluation)
The interlayer films for laminated glass obtained in Examples and Comparative Examples were evaluated by the following methods. The results are shown in Table 1.

(1) Measurement of Ry value The maximum height (Ry) of both surfaces of the obtained interlayer film for laminated glass was measured by a method according to JIS B 0601 (1994). “Surfcoder SE300” manufactured by Kosaka Laboratory Co., Ltd. was used as the measuring instrument, and the stylus meter conditions at the time of measurement were cut-off value = 2.5 mm, reference length = 2.5 mm, evaluation length = 12.5 mm, stylus The measurement was performed under the conditions of the tip radius = 2 μm, the tip angle = 60 °, and the measurement speed = 0.5 mm / s. The environment during the measurement was 23 ° C. and 30 RH%. The direction in which the stylus is moved is a direction parallel to the flow direction of the sheet, and an average value of the respective values measured by shifting 20 times at a pitch of 3 mm in the width direction is calculated as the value of Ry. In addition, as an index of variation in Ry, a CV value of 20 measured values was calculated.
The obtained Ry value was the same on both sides.

(2) Measurement of Sm value By the method according to JIS B 0601 (1994), the average interval (Sm) of the unevenness on both surfaces of the obtained interlayer film for laminated glass was measured. “Surfcoder SE300” manufactured by Kosaka Laboratory Co., Ltd. was used as the measuring instrument, and the stylus meter conditions at the time of measurement were cut-off value = 2.5 mm, reference length = 2.5 mm, evaluation length = 12.5 mm, stylus The measurement was performed under the conditions of the tip radius = 2 μm, the tip angle = 60 °, and the measurement speed = 0.5 mm / s. The environment during the measurement was 23 ° C. and 30 RH%. The direction in which the stylus is moved is a direction parallel to the sheet flow direction, and an average value of the respective values measured by shifting 20 times at a pitch of 3 mm in the width direction is calculated as the value of Sm. Further, as an index of Sm variation, a CV value of 20 measured values was calculated.
The obtained Sm value was the same on both sides.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the intermediate film for laminated glasses which can provide a uniform unevenness | corrugation on the surface by the extrusion lip embossing method using a melt fracture can be provided.

Claims (3)

A method for producing an interlayer film for laminated glass having a large number of irregularities on at least one surface,
Preparing a raw resin composition so that the melt viscosity at the extrusion temperature is 2.5 × 10 ⁴ Pa · s or more;
A method for producing an interlayer film for laminated glass, comprising a step of imparting a number of irregularities to at least one surface of the interlayer film for laminated glass by an extrusion lip embossing method using a melt fracture. 2. The intermediate for laminated glass according to claim 1, wherein the raw material resin composition is prepared by blending the particulate material so that the melt viscosity at the extrusion temperature is 2.5 × 10 ⁴ Pa · s or more. A method for producing a membrane. The method for producing an interlayer film for laminated glass according to claim 2, wherein the particulate material is a pigment.