WO2019168173A1

WO2019168173A1 - Multilayer structure in which plasticizer-containing sheets are stacked

Info

Publication number: WO2019168173A1
Application number: PCT/JP2019/008177
Authority: WO
Inventors: 芳聡淺沼; 淳小石川; 磯上　宏一郎
Original assignee: 株式会社クラレ
Priority date: 2018-03-01
Filing date: 2019-03-01
Publication date: 2019-09-06
Also published as: JPWO2019168173A1; KR20200128013A

Abstract

Provided is a multilayer structure of sheets having an electroconductive structure, the multilayer structure having exceptional transparency and being usable during production of laminated glass, wherein defects do not readily form in the electroconductive structure during production of laminated glass, and the multilayer structure creates laminated glass that has exceptional workability and is provided with a level of safety required for safe laminated glass. This multilayer structure is obtained by stacking two or more sheets (A) provided with a polyvinyl acetal layer (1) that includes 100 parts by mass of polyvinyl acetal (1) and 0-200 parts by mass of a plasticizer, a polyvinyl acetal layer (2) that includes 100 parts by mass of polyvinyl acetal (2) and 0-200 parts by mass of a plasticizer, and an electroconductive structure that is disposed between the layer (1) and the layer (2), wherein the total plasticizer content included in the sheet (A) is 10-80 parts by mass, where the total polyvinyl acetal (1) and (2) content included in the sheet (A) is 100 parts by mass.

Description

Multilayer structure in which plasticizer-containing sheets overlap

The present invention relates to a multilayer structure in which two or more plasticizer-containing sheets having a conductive structure are stacked.

A method for removing icing and fogging of windshields or the like is required for glass in buildings or vehicles, such as automobiles, and conventionally, a method of applying hot air to glass is known as this method. However, this method has a problem that it takes time to obtain sufficient forward visibility. Especially in electric vehicles that cannot use the combustion heat of gasoline fuel to remove icing and fogging, there is a problem that the method of heating air with electricity and applying hot air to glass is inefficient and directly leads to a decrease in cruising distance. .

Therefore, there has been proposed a method of removing icing and fogging by installing a conductive structure on glass and energizing it. For example, Patent Document 1 includes a transparent base material, an adhesive layer provided on at least one surface of the transparent base material, a conductive heating wire provided on the adhesive layer, the conductive heating wire, and the heating wire. A heating film including a coating film that encapsulates an upper surface of an uncovered adhesive layer, a bus bar electrically connected to the conductive heating wire, and a power supply unit connected to the bus bar is described. Describes an example using a PET (polyethylene terephthalate) film as a transparent substrate. For example, Patent Document 2 discloses a method of manufacturing a laminated glass having a conductive structure by disposing and bonding at least one sheet A and at least one sheet B between two transparent plates. The sheet A contains a polyvinyl acetal PA and a plasticizer WA, and has a discontinuous conductive structure, and the sheet B describes a method containing a polyvinyl acetal PB and a plasticizer WB. ing.

JP 2000-119047 A Special table 2016-539905 gazette

By the way, when producing a laminated glass having a conductive structure, a resin sheet having a conductive structure may be used. A resin sheet having such a conductive structure can have any conductive structure and can be produced by an economical method, but better handling during transportation or storage may be required. When transporting from production site to use site and when storing at production site or use site, the resin sheet with conductive structure is rolled up or cut into two or more sheets and stacked in a compact state. It is preferable from the viewpoint of handleability. However, when transported or stored in such a form, the conductive structure may break or peel from the resin sheet at the part where the resin sheets overlap each other, and further the resin sheet on which the conductive structure overlaps When the resin sheet is pulled out from the roll, the conductive structure may be disconnected. Such breakage, peeling, or disconnection of the conductive structure is a cause of deteriorating the appearance of the finally obtained laminated glass and a cause of reducing the conductivity and heating performance. Moreover, the performance (safety) as a safety laminated glass may be insufficient only with a resin sheet having a conventional conductive structure, and in that case, it is necessary to use a commonly used interlayer film for laminated glass. However, when using an interlayer film for laminated glass together, many processes such as cutting out both the resin sheet and the interlayer film for laminated glass into a glass size in the process of producing the laminated glass and sandwiching them between the glass Is necessary, which is not preferable in terms of workability. In particular, in the process of manufacturing an automated interlayer film for laminated glass in recent years, if another resin sheet is used in addition to the interlayer film for laminated glass, it is necessary to make a significant change in the manufacturing process. It was difficult.

The present invention solves the above problems. That is, the present invention is a multi-layer structure of a sheet having a conductive structure that has excellent transparency and can be used in the production of laminated glass, and has defects such as breakage, peeling and disconnection in the conductive structure during the production of laminated glass. An object of the present invention is to provide a multilayer structure that is less likely to occur, has excellent workability, and provides a laminated glass having safety required for a laminated safety glass.

In order to solve the above problems, the present inventors have studied in detail a multilayer structure in which sheets having a conductive structure disposed between two polyvinyl acetal layers are overlapped to complete the present invention. It came to.

That is, the present invention includes the following preferred embodiments.
[1] Polyvinyl acetal layer (1) containing 100 parts by mass of polyvinyl acetal (1) and 0 to 200 parts by mass of plasticizer, and polyvinyl acetal layer containing 100 parts by mass of polyvinyl acetal (2) and 0 to 200 parts by mass of plasticizer (2) and a multilayer structure in which two or more sheets (A) comprising the polyvinyl acetal layer (1) and the conductive structure disposed between the polyvinyl acetal layer (2) are overlapped, When the total content of the polyvinyl acetal (1) and the polyvinyl acetal (2) contained in the sheet (A) is 100 parts by mass, the total content of the plasticizer contained in the sheet (A) is 10 to 80 parts by mass. A multilayer structure.
[2] At least one of the content of the plasticizer contained in the polyvinyl acetal layer (1) and the content of the plasticizer contained in the polyvinyl acetal layer (2) is 10 parts by mass or more. Multilayer structure.
[3] One of the content of the plasticizer contained in the polyvinyl acetal layer (1) and the content of the plasticizer contained in the polyvinyl acetal layer (2) is 0 to 10 parts by mass, and The multilayer structure according to [1] or [2], wherein one is 10 parts by mass or more and 80 parts by mass or less.
[4] The multilayer structure according to any one of [1] to [3], wherein the sheet (A) has an uneven structure on at least one surface thereof.
[5] The multilayer structure according to [4], wherein the average surface roughness of at least one surface of the sheet (A) is 15 to 70 μm.
[6] The multilayer structure according to any one of [1] to [5], wherein the sheet (A) is wound on a winding core in a multilayer structure formed in a roll shape.
[7] The multilayer structure according to any one of [1] to [6], wherein the conductive structure is a heat generating conductive structure.
[8] The multilayer structure according to any one of [1] to [7], wherein the conductive structure is an etching structure of a metal foil.
[9] The multilayer structure according to [8], wherein the metal foil contains copper.
[10] The multilayer structure includes an adhesive layer between at least one of the polyvinyl acetal layer (1) and the conductive structure and between the polyvinyl acetal layer (2) and the conductive structure. A multilayer structure according to any one of the above [1] to [9].
[11] The multilayer structure does not have an adhesive layer between the polyvinyl acetal layer (1) and the conductive structure, and between the polyvinyl acetal layer (2) and the conductive structure. The multilayer structure according to any one of [1] to [9].
[12] The multilayer structure according to any one of [1] to [11], wherein the degree of polymerization of at least one of the polyvinyl acetal (1) and the polyvinyl acetal (2) is 800 or more.
[13] The multilayer structure according to any one of [1] to [12], wherein the degree of polymerization of the polyvinyl acetal (1) is less than 1500 and the degree of polymerization of the polyvinyl acetal (2) is 1500 or more.
[14] The polyvinyl acetal (1) is represented by the formula (1):

The polyvinyl acetal (2) has the structure represented by formula (2):

Wherein R1 and R2 are each independently a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and R1 and R2 have the same carbon number. The multilayer structure according to any one of [1] to [13].
[15] When the degree of acetalization of the polyvinyl acetal (1) is A ₁ mol% and the degree of acetalization of the polyvinyl acetal (2) is A ₂ mol%, the absolute value of the difference between A ₁ and A ₂ is The multilayer structure according to any one of [1] to [14], which is less than 5 mol%.
[16] When the amount of hydroxyl group of the polyvinyl acetal (1) is ₁ mol% and the amount of hydroxyl group of the polyvinyl acetal (2) is ₂ mol%, the absolute value of the difference between H ₁ and H ₂ is 5 mol. % Of the multilayer structure according to any one of [1] to [15].
[17] The plasticizer content in the polyvinyl acetal layer (1) is smaller than the plasticizer content in the polyvinyl acetal layer (2), and the degree of polymerization of the polyvinyl acetal (1) is that of the polyvinyl acetal (2). The multilayer structure according to any one of [1] to [16], which has a degree of polymerization smaller than that.
[18] The multilayer structure according to any one of [1] to [17], wherein the plasticizer includes an ether ester compound.
[19] Two sheets (A) are stacked so that the surface on the polyvinyl acetal layer (1) side and the surface on the polyvinyl acetal layer (2) side are in contact with each other, and are perpendicular to the surface at 23 ° C. and 50% RH. The multilayer structure according to any one of the above [1] to [18], wherein the peeling force showing blocking resistance after applying a pressure of 0.02 MPa for 48 hours in the direction is 30 N / 30 mm or less.
[20] The degree of polymerization of the polyvinyl acetal (1) is smaller than the degree of polymerization of the polyvinyl acetal (2), and the thickness of the polyvinyl acetal layer (1) is smaller than the thickness of the polyvinyl acetal layer (2). [1] A multilayer structure according to any one of [19].
[21] Tg _{1 is} a temperature at which tan δ of the composition constituting the polyvinyl acetal layer (1) takes a maximum value, and Tg _{2 is a} temperature at which tan δ of the composition constituting the polyvinyl acetal layer (2) takes a maximum value. The multilayer structure according to any one of [1] to [20], wherein at least one of Tg ₁ and Tg ₂ is 5 ° C. or higher.
[22] The multilayer structure according to any one of [1] to [21], wherein the sheet (A) has a terminal for receiving an electric power or an electric signal disposed so as to protrude outward.

According to the present invention, it is a multilayer structure of a sheet having a conductive structure that has excellent transparency and can be used in the production of laminated glass, and when the laminated glass is produced, defects such as breakage, peeling and disconnection occur in the conductive structure. A multilayer structure that provides a laminated glass that is difficult and has excellent workability and has the safety required for a laminated safety glass is provided.

The multilayer structure of the present invention is a multilayer structure in which two or more sheets (A) are overlapped. In the present invention, the “multilayer structure in which two or more sheets (A) are overlapped” means that the sheet (A) is cut into a certain size and two or more sheets are stacked or wound in a roll shape. Means a state in which two or more sheets (A) are overlapped (that is, a state in which they are overlapped in a roll shape). The sheet (A) comprises 100 parts by weight of polyvinyl acetal (1) and a polyvinyl acetal layer (1) containing 0 to 200 parts by weight of a plasticizer, 100 parts by weight of polyvinyl acetal (2) and 0 to 200 parts by weight of a plasticizer. A polyvinyl acetal layer (2), a polyvinyl acetal layer (1), and a conductive structure disposed between the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2). ) And polyvinyl acetal (2) in a total content of 100 parts by mass, the total content of the plasticizer contained in the sheet (A) is 10 to 80 parts by mass.

<Polyvinyl acetal (1) and polyvinyl acetal (2)>
As the polyvinyl acetal (1) and the polyvinyl acetal (2), a polyvinyl acetal resin produced by acetalization of a polyvinyl alcohol resin such as polyvinyl alcohol or an ethylene vinyl alcohol copolymer can be used. The polyvinyl acetal resin constituting the polyvinyl acetal (1) and the polyvinyl acetal resin constituting the polyvinyl acetal (2) may be the same or different.

The polyvinyl acetal (1) may be composed of a single polyvinyl acetal resin. The degree of polymerization, the degree of acetalization, the amount of acetyl groups, the amount of hydroxyl groups, the ethylene content, the molecular weight of the aldehyde used for acetalization, and the chain length Any one or more of them may be composed of two or more different polyvinyl acetal resins. When the polyvinyl acetal (1) is composed of two or more polyvinyl acetal resins different from each other, from the viewpoint of ease of melt molding, deformation of the conductive structure during the production of laminated glass, deviation of the glass when using the laminated glass, etc. From the viewpoint of preventing the above, the polyvinyl acetal (1) is a mixture of two or more polyvinyl acetal resins having different polymerization degrees or an acetalization product of a mixture of at least two polyvinyl alcohol resins having different viscosity average polymerization degrees. It is preferable. The matters described in this paragraph are the same for the polyvinyl acetal (2).

Polyvinyl acetal (1) and polyvinyl acetal (2) can be produced, for example, by the following method, but are not limited thereto. First, an aqueous solution of polyvinyl alcohol or ethylene vinyl alcohol copolymer having a concentration of 3 to 30% by mass is maintained in a temperature range of 80 to 100 ° C. and then gradually cooled over 10 to 60 minutes. When the temperature drops to −10 to 30 ° C., an aldehyde and an acid catalyst are added, and an acetalization reaction is performed for 30 to 300 minutes while keeping the temperature constant. Next, the temperature of the reaction solution is raised to a temperature of 20 to 80 ° C. over 30 to 200 minutes and held for 30 to 300 minutes. Then, after filtering a reaction liquid as needed, neutralizing agents, such as an alkali, are added and neutralized, and a polyvinyl acetal resin is obtained by filtering resin, washing with water, and drying.

The acid catalyst used in the acetalization reaction is not particularly limited, and organic acids and inorganic acids such as acetic acid, paratoluenesulfonic acid, nitric acid, sulfuric acid and hydrochloric acid can be used. Among these, hydrochloric acid, sulfuric acid, and nitric acid are preferable from the viewpoint of acid strength and ease of removal during washing.

The polyvinyl acetal (1) and the polyvinyl acetal (2) are preferably those obtained by acetalizing at least one polyvinyl alcohol-based resin with one or more aldehydes or keto compounds having 2 to 10 carbon atoms. . Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol and ethylene vinyl alcohol copolymer, and polyvinyl alcohol is preferable. The aldehyde or keto compound may be linear, branched or cyclic, preferably linear or branched, more preferably a linear aliphatic aldehyde, n- Particularly preferred is butyraldehyde. When it is the said aspect, polyvinyl acetal (1) and polyvinyl acetal (2) tend to have suitable breaking energy. Further, the polyvinyl acetal (1) and the polyvinyl acetal (2) may be an acetalized product of a mixture of a plurality of aldehydes or keto compounds, and the content of n-butyraldehyde in the mixture is preferably 50% by mass or more, 80 mass% or more is more preferable, 95 mass% or more is further more preferable, 99 mass% or more is especially preferable, and 100 mass% may be sufficient.

The polyvinyl alcohol resin used in the production of the polyvinyl acetal (1) and the polyvinyl acetal (2) may be a single resin, or two or more polyvinyl alcohol resins having different viscosity average polymerization degrees or hydrolysis degrees. It may be a mixture. The viscosity average polymerization degree of the polyvinyl alcohol resin is preferably 400 or more, more preferably 800 or more, further preferably 1000 or more, particularly preferably 1300 or more, and most preferably 1500 or more. When the viscosity average polymerization degree is equal to or higher than the lower limit, deformation and disconnection of the conductive structure are easily suppressed during the production of the laminated glass, and the phenomenon that the glass is displaced due to heat in the obtained laminated glass is easily prevented. The viscosity average degree of polymerization is preferably 5000 or less, more preferably 3000 or less, further preferably 2500 or less, particularly preferably 2300 or less, and most preferably 2000 or less. When the viscosity average polymerization degree is not more than the above upper limit value, it is easy to obtain good film forming properties. The viscosity average degree of polymerization is measured based on JIS K 6726 “Testing method for polyvinyl alcohol”. When the polyvinyl alcohol resin is composed of two or more different polyvinyl alcohol resins, the viscosity average polymerization degree of at least one polyvinyl alcohol resin is preferably not less than the lower limit and not more than the upper limit.

In a preferred embodiment, the degree of polymerization of at least one of the polyvinyl acetal (1) and the polyvinyl acetal (2) is 800 or more, more preferably 900 or more, still more preferably 1000 or more, particularly preferably 1300 or more, and most preferably 1500. That's it. The preferable upper limit value of the polymerization degree in this embodiment is the same as the preferable upper limit value of the viscosity average polymerization degree of the polyvinyl alcohol resin. When the degree of polymerization of at least one of the polyvinyl acetal (1) and the polyvinyl acetal (2) is equal to or higher than the lower limit, deformation and disconnection of the conductive structure are easily suppressed during the production of the laminated glass, and the resulting laminated glass is heated by heat. The phenomenon of slippage is easily prevented. In the present invention, the degree of polymerization of the polyvinyl acetal resin means a value measured based on JIS K6728 (1977).

In a preferred embodiment, the degree of polymerization of polyvinyl acetal (1) is less than 1500, and the degree of polymerization of polyvinyl acetal (2) is 1500 or more. The degree of polymerization of the polyvinyl acetal (1) is more preferably less than 1450, even more preferably less than 1400, particularly preferably less than 1350, and most preferably less than 1300. The degree of polymerization of the polyvinyl acetal (2) is more preferably 1550 or more, further preferably 1580 or more, particularly preferably 1600 or more, and most preferably 1620 or more. When the polymerization degree of the polyvinyl acetal (1) is less than the above upper limit value and the polymerization degree of the polyvinyl acetal (2) is not less than the above lower limit value, when the sheet (A) is used as an interlayer film for laminated glass, the transparency Excellent in penetration resistance. The preferable lower limit of the degree of polymerization of the polyvinyl acetal (1) in this embodiment is the same as the preferable lower limit of the viscosity average degree of polymerization of the polyvinyl alcohol resin described above, and the preferable upper limit of the degree of polymerization of the polyvinyl acetal (2) is The upper limit value of the viscosity average polymerization degree of the polyvinyl alcohol resin is the same as that described above.

The amount of acetyl groups in the polyvinyl acetal (1) and the polyvinyl acetal (2) is preferably 0.1 to 20 mol%, more preferably 0.5 to 8 mol%, based on the ethylene unit of the polyvinyl acetal main chain. More preferably, it is 0.5 to 3 mol% or 5 to 8 mol%. The amount of the acetyl group can be adjusted by appropriately adjusting the degree of saponification of the raw material polyvinyl alcohol resin. When the amount of the acetyl group is within the above range, the plasticizer compatibility and mechanical strength of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) tend to be excellent, and the polyvinyl acetal layer (1) and the polyvinyl acetal layer (1) Good bondability with the acetal layer (2), reduction of optical distortion, and the like are easily achieved. When the polyvinyl acetal (1) or the polyvinyl acetal (2) contains two or more different polyvinyl acetal resins, the average acetyl group amount of the polyvinyl acetal (1) or the average acetyl group amount of the polyvinyl acetal (2) is It is preferable to be within the above range.

The degree of acetalization of the polyvinyl acetal (1) and the polyvinyl acetal (2) is not particularly limited, but is preferably 40 to 86 mol%, more preferably 45 to 84 mol%, still more preferably 50 to 82 mol%, particularly preferably. 60 to 82 mol%, most preferably 68 to 82 mol%. By appropriately adjusting the amount of aldehyde used in the acetalization reaction, the acetalization degree can be adjusted within the above range. When the degree of acetalization is within the above range, the mechanical strength of the sheet (A) in the present invention is likely to be sufficient, and the compatibility between the polyvinyl acetal (1) and the polyvinyl acetal (2) and the plasticizer is hardly lowered. When the polyvinyl acetal (1) or the polyvinyl acetal (2) contains two or more different polyvinyl acetal resins, the average acetalization degree of the polyvinyl acetal (1) or the average acetalization degree of the polyvinyl acetal (2) is It is preferable to be within the above range.

In a preferred embodiment, the absolute value of the difference between A ₁ and A ₂ when the degree of acetalization of the polyvinyl acetal (1) is A ₁ mol% and the degree of acetalization of the polyvinyl acetal (2) is A ₂ mol%. Is less than 5 mol%. The absolute value is more preferably less than 3 mol%, particularly preferably less than 1 mol%, most preferably 0 mol%. When the absolute value is less than the above upper limit value or 0 mol%, the transparency of the sheet (A) is easily obtained.

The amount of hydroxyl groups in the polyvinyl acetal (1) and the polyvinyl acetal (2) is preferably 16 to 34 mol%, more preferably 18 to 34 mol%, more preferably 22 to 34, based on the ethylene unit of the polyvinyl acetal main chain. Mol%, particularly preferably 26 to 34 mol%, and more preferably 9 to 29 mol%, more preferably 12 to 26 mol%, still more preferably 15 to 23 mol%, particularly for providing sound insulation performance together Preferably, it is 16 to 20 mol%. By adjusting the amount of aldehyde used in the acetalization reaction, the amount of hydroxyl groups can be adjusted within the above range. When the amount of hydroxyl groups is within the above range, the difference in refractive index between the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) becomes small, and it is easy to obtain a laminated glass with little optical unevenness. When the polyvinyl acetal (1) or the polyvinyl acetal (2) contains two or more different polyvinyl acetal resins, the average hydroxyl group amount of the polyvinyl acetal (1) or the average hydroxyl group amount of the polyvinyl acetal (2) is within the above range, respectively. It is preferable to be within.

In a preferred embodiment, the absolute value of the difference between H ₁ and H ₂ when the amount of hydroxyl group of polyvinyl acetal (1) is ₁ mol% and the amount of hydroxyl group of polyvinyl acetal (2) is ₂ mol% is 5 Less than mol%. The absolute value is more preferably less than 3 mol%, particularly preferably less than 1 mol%, most preferably 0 mol%. When the absolute value is less than the above upper limit value or 0 mol%, the transparency of the sheet (A) is easily obtained. On the other hand, when the sheet (A) is used as an interlayer film for laminated glass by making a difference between H ₁ and H ₂ , the amount of plasticizer in the polyvinyl acetal layer (1) in the equilibrium state after the plasticizer has migrated It is also possible to obtain a laminated glass excellent in sound insulation performance by making a difference in the amount of plasticizer in the polyvinyl acetal layer (2). In that case, the difference between H ₁ and H ₂ is preferably 5 mol% or more, more preferably 8 mol% or more.

The polyvinyl acetal (1) and the polyvinyl acetal (2) are usually composed of an acetal group unit, a hydroxyl group unit, and an acetyl group unit, and the amount of each unit is JIS K 6728 “Testing method for polyvinyl butyral” or nuclear magnetic field. Measured by resonance method (NMR).

Polyvinyl acetal (1) and polyvinyl acetal (2) measured at 20 ° C. and 30 rpm using a Brookfield type (B type) viscometer, 10% by weight toluene / ethanol = 1/1 (mass ratio) The viscosity of the solution is preferably 200 mPa · s or more, more preferably 240 mPa · s or more, and particularly preferably 265 mPa · s or more. By using a polyvinyl alcohol resin having a high viscosity average degree of polymerization as at least a part of the raw material, the viscosity can be adjusted to the lower limit value or more. When the polyvinyl acetal (1) or the polyvinyl acetal (2) is a mixture of two or more polyvinyl acetal resins different from each other, the viscosity of the mixture is preferably equal to or higher than the lower limit value. When the viscosity is equal to or higher than the lower limit, deformation and disconnection of the conductive structure are easily suppressed during the production of the laminated glass, and the phenomenon that the glass is displaced due to heat in the obtained laminated glass is easily prevented. The upper limit of the viscosity is usually 1000 mPa · s, preferably 800 mPa · s, more preferably 500 mPa · s, still more preferably 450 mPa · s, particularly preferably 400 mPa · s, from the viewpoint of easily obtaining good film forming properties. It is.

The peak top molecular weight of the polyvinyl acetal (1) and the polyvinyl acetal (2) is preferably 115,000 to 200,000, more preferably 120,000 to 160,000, particularly preferably 130,000 to 150,000. . By using a polyvinyl alcohol resin having a high viscosity average polymerization degree as at least a part of the raw material, the peak top molecular weight can be adjusted within the above range. When the peak top molecular weight is within the above range, it is easy to obtain suitable film-forming properties and suitable film properties (for example, laminate suitability, creep resistance, and breaking strength).
The molecular weight distribution of the polyvinyl acetal (1) and the polyvinyl acetal (2), that is, the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably 2.7 or more, more preferably 2 .8 or more, particularly preferably 2.9 or more. The molecular weight distribution can be adjusted to the lower limit value or more by acetalizing a mixture of polyvinyl alcohol resins having different viscosity average polymerization degrees or by mixing polyvinyl acetal resins having different polymerization degrees. When the molecular weight distribution is not less than the lower limit value, it is easy to achieve both film-forming properties and suitable film properties (for example, suitability for lamination, creep resistance, and breaking strength). The upper limit of the molecular weight distribution is not particularly limited, but is usually 10 and preferably 5 from the viewpoint of ease of film formation.
When the polyvinyl acetal (1) or the polyvinyl acetal (2) contains two or more different polyvinyl acetal resins, the peak top molecular weight and molecular weight distribution of at least one polyvinyl acetal resin are preferably within the above ranges. The peak top molecular weight and molecular weight distribution are determined using gel permeation chromatography (GPC) and polystyrene having a known molecular weight as a standard.

In a preferred embodiment, the polyvinyl acetal (1) has the formula (1):

The polyvinyl acetal (2) has the structure represented by the formula (2):

Wherein R1 and R2 are each independently a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and R1 and R2 have the same carbon number, More preferably, R1 and R2 are the same group.

The ratio of the structure represented by the formula (1) contained in the polyvinyl acetal (1) to the acetal ring structure contained in the polyvinyl acetal (1), and the formula (2) contained in the polyvinyl acetal (2) The ratio of the structure to the acetal ring structure contained in the polyvinyl acetal (2) is not particularly limited, but is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol. % Or more. By appropriately selecting the type and amount of aldehyde used in the acetalization reaction, the ratio of the structure of formula (1) contained in polyvinyl acetal (1) and the structure of formula (2) contained in polyvinyl acetal (2) Can be adjusted to the above lower limit or more. It is easy to obtain the sheet | seat (A) excellent in transparency as the said ratio is more than the said lower limit. The upper limit of the ratio is 100 mol%. The said ratio is calculated | required by the nuclear magnetic resonance method, for example.

R1 and R2 are aliphatic hydrocarbon groups (for example, methyl group, ethyl group, n-propyl group and isopropyl group), aromatic hydrocarbon groups (for example, phenyl group) or hydrogen atoms (0 carbon atoms). The group includes a group in which an arbitrary hydrogen atom of an aliphatic hydrocarbon group is replaced with another group, and a group in which an arbitrary hydrogen atom of an aromatic hydrocarbon group is replaced with another group. Among these, an aliphatic hydrocarbon group is preferable, an aliphatic hydrocarbon group having 1 to 7 carbon atoms is more preferable, and an aliphatic hydrocarbon group is more preferable from the viewpoint of easily obtaining high compatibility with a plasticizer, appropriate processability, and mechanical strength. An aliphatic hydrocarbon group of 2 to 4 is more preferable, and an n-propyl group (the chemical structure of the formula (1) or the formula (2) is a butyral ring structure) is particularly preferable.

The polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) preferably contain an uncrosslinked polyvinyl acetal resin from the viewpoint of easily obtaining good film forming properties, but may contain a crosslinked polyvinyl acetal. . Methods for crosslinking polyvinyl acetal are, for example, EP 1527107B1 and WO 2004/062311 A1 (thermal self-crosslinking of carboxyl group-containing polyvinyl acetal), EP 1606325 A1 (polyvinyl acetal crosslinked with polyaldehyde), and WO 2003 / 020776 A1 (polyvinyl acetal crosslinked with glyoxylic acid). It is also a useful method to control the amount of intermolecular acetal bonds produced and to control the degree of blocking of residual hydroxyl groups by appropriately adjusting the acetalization reaction conditions.

<Plasticizer>
The amount of plasticizer contained in the polyvinyl acetal layer (1) is 0 to 200 parts by mass with respect to 100 parts by mass of the polyvinyl acetal (1), and the amount of plasticizer contained in the polyvinyl acetal layer (2) is When the total content of the polyvinyl acetal (1) and the polyvinyl acetal (2) contained in the sheet (A) is 100 parts by mass with respect to 100 parts by mass of the acetal (2), the sheet ( The total content of plasticizers contained in A) is 10 to 80 parts by mass. When the plasticizer content does not satisfy the above conditions, defects such as breakage, peeling and disconnection in the conductive structure are extremely likely to occur during the production of the laminated glass, and a laminated glass having the safety required for the safety laminated glass is provided. I can't. Further, when the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) do not contain a specific resin and a specific amount of plasticizer, good transparency, difficulty in generating defects in the above-described conductive structure, and matching It is not possible to obtain a sheet having both excellent workability during glass production and the ability to impart safety to the laminated glass described above.

From the viewpoint of easily obtaining a sheet (A) having good transparency, excellent workability at the time of producing the above-described conductive structure and laminated glass, and the ability to impart safety to the above-mentioned laminated glass, a polyvinyl acetal layer (1 ) Is preferably 0 to 80 parts by weight, more preferably 0 to 60 parts by weight, and still more preferably 0 to 50 parts by weight with respect to 100 parts by weight of the polyvinyl acetal (1). The amount of the plasticizer in the polyvinyl acetal layer (2) is preferably 0 to 80 parts by mass, more preferably 0 to 60 parts by mass, and further preferably 0 to 50 parts by mass with respect to 100 parts by mass of the polyvinyl acetal (2). It is. When the total content of the polyvinyl acetal (1) and the polyvinyl acetal (2) contained in the sheet (A) is 100 parts by mass, the total content of the plasticizer contained in the sheet (A) is preferably 15 to 80 The mass is more preferably 15 to 70 parts by mass, still more preferably 20 to 60 parts by mass.

When the sheet (A) is treated at a high temperature condition used at the time of producing laminated glass, for example, at 140 ° C. for 30 minutes or more, the plasticizers contained in the polyvinyl acetal layer (1) and / or the polyvinyl acetal layer (2) migrate to each other. . In the case where the sheet (A) contains the amount of the plasticizer, the sheet after the heat treatment exhibits suitable flexibility and excellent mechanical strength, and thus is particularly suitable for use as an interlayer film for laminated glass. The sheet after the heat treatment is likely to exhibit appropriate flexibility and excellent mechanical strength. Therefore, when the sheet (A) is used as an interlayer film for laminated glass, it is easy to obtain a laminated glass with better safety. Therefore, when the heat-treated sheet is evaluated by dynamic viscoelasticity, a tan δ peak temperature preferably appears below 5 to 50 ° C., and a tan δ peak temperature appears more preferably below 20 to 35 ° C.

In a preferred embodiment, at least one of the content of the plasticizer contained in the polyvinyl acetal layer (1) and the content of the plasticizer contained in the polyvinyl acetal layer (2) is 10 parts by mass or more, more preferably 20 It is at least 30 parts by mass, particularly preferably at least 30 parts by mass. When content of a plasticizer satisfy | fills the said conditions, when using the sheet | seat (A) in this invention as an intermediate film for laminated glasses, it is easy to obtain the penetration resistance excellent.

In another preferred embodiment, one of the content of the plasticizer contained in the polyvinyl acetal layer (1) and the content of the plasticizer contained in the polyvinyl acetal layer (2) is 0 to 10 parts by mass. And the other is 10 parts by mass or more and 80 parts by mass or less. Particularly preferably, one of the content of the plasticizer contained in the polyvinyl acetal layer (1) and the content of the plasticizer contained in the polyvinyl acetal layer (2) is 0 part by mass or more and 5 parts by mass or less. One is 20 parts by mass or more and 60 parts by mass or less. When the plasticizer content satisfies the above condition, when the sheet (A) in the present invention is used as an interlayer film for laminated glass, it is easy to obtain low self-adhesion and excellent penetration resistance.

Moreover, in another preferable one aspect | mode, content of the plasticizer in a polyvinyl acetal layer (1) is smaller than content of the plasticizer in a polyvinyl acetal layer (2), and the polymerization degree of polyvinyl acetal (1) is polyvinyl acetal. It is smaller than the degree of polymerization of (2). When the plasticizer content and the degree of polymerization satisfy the above conditions, when the sheet (A) in the present invention is used as an interlayer film for laminated glass, excellent handleability and penetration resistance are easily obtained.

One or more compounds from the following group are preferably used as plasticizers.
-Esters of polyvalent aliphatic or aromatic acids. For example, dialkyl adipates (eg, dihexyl adipate, di-2-ethylbutyl adipate, dioctyl adipate, di-2-ethylhexyl adipate, hexyl cyclohexyl adipate, heptyl adipate, nonyl adipate, diisononyl adipate, heptyl nonyl adipate); adipic acid and alcohol Or esters with alcohols containing ether compounds (eg di (butoxyethyl) adipate, di (butoxyethoxyethyl) adipate); dialkyl sebacates (eg dibutyl sebacate); including sebacic acid and alicyclic or ether compounds Esters with alcohols; esters of phthalic acid (eg butylbenzyl phthalate, bis-2-butoxyethyl phthalate); and alicyclic polyvalent carboxylic acids And esters of aliphatic alcohols (e.g., 1,2-cyclohexane dicarboxylic acid diisononyl esters).
Polyhydric aliphatic or aromatic alcohols or oligoether glycol esters or ethers having one or more aliphatic or aromatic substituents. Examples thereof include esters of glycerin, diglycol, triglycol, tetraglycol and the like with a linear or branched aliphatic or alicyclic carboxylic acid. Specifically, diethylene glycol-bis- (2-ethylhexanoate), triethylene glycol-bis- (2-ethylhexanoate), triethylene glycol-bis- (2-ethylbutanoate), tetraethylene Ethers such as glycol-bis- (2-ethylhexanoate), tetraethylene glycol-bis-n-heptanoate, triethylene glycol-bis-n-heptanoate, triethylene glycol-bis-n-hexanoate, dipropylene glycol benzoate Examples thereof include ester compounds and tetraethylene glycol dimethyl ether.
-Phosphate esters of aliphatic or aromatic alcohols. Examples include tris (2-ethylhexyl) phosphate (TOP), triethyl phosphate, diphenyl-2-ethylhexyl phosphate, and tricresyl phosphate.
-Esters of citric acid, succinic acid and / or fumaric acid.
-Ethylene oxide and / or propylene oxide adduct of bisphenol A.

In addition, polyesters or oligoesters composed of polyhydric alcohol and polycarboxylic acid, terminal esterified products or etherified products thereof, polyesters or oligoesters composed of lactone or hydroxycarboxylic acid, or terminal esterified products or etherified products thereof. It may be used as a plasticizer.

From the viewpoint of suppressing problems (for example, problems such as changes in physical properties over time) associated with the migration of the plasticizer between the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2), the polyvinyl acetal layer (1) Are the same as those in the polyvinyl acetal layer (2) or the physical properties of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) (for example, heat resistance, light resistance, transparent It is preferable to use a plasticizer that does not impair the properties and plasticization efficiency. From this point of view, ether ester compounds are preferred as plasticizers, and include triethylene glycol-bis- (2-ethylhexanoate), triethylene glycol-bis (2-ethylbutanoate), tetraethylene glycol- Bis- (2-ethylhexanoate) and tetraethylene glycol-bisheptanoate are more preferred, and triethylene glycol-bis- (2-ethylhexanoate) is particularly preferred.

<Additives>
The polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) may further contain another additive. Such additives include, for example, water, UV absorbers, antioxidants, adhesion modifiers, brighteners or fluorescent brighteners, stabilizers, dyes, processing aids, organic or inorganic nanoparticles, fired silica. Examples include acids and surfactants.

In an embodiment, it is preferable that the sheet (A) contains a corrosion inhibitor in order to suppress corrosion of the conductive structure contained in the sheet (A). In such a case, the corrosion inhibitor is preferably contained in the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2). The amount of the corrosion inhibitor contained in the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) is preferably 0.005 to 5 based on the mass of the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2). % By mass. Examples of corrosion inhibitors include substituted or unsubstituted benzotriazole.

The composition constituting the polyvinyl acetal layer (1) and the composition constituting the polyvinyl acetal layer (2) may have the same composition or different compositions.

<Method for Producing Polyvinyl Acetal Layer (1) and Polyvinyl Acetal Layer (2)>
The manufacturing method of a polyvinyl acetal layer (1) and a polyvinyl acetal layer (2) is not specifically limited. After blending the polyvinyl acetal resin, optionally a predetermined amount of plasticizer, and other additives as necessary, and uniformly kneading this, extrusion method, calendar method, press method, casting method, inflation method, etc. A sheet (layer) is produced by a known film forming method, and this can be used as the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2).

Among known film forming methods, a method of producing a sheet (layer) using an extruder is particularly preferably employed. The resin temperature at the time of extrusion is preferably 150 to 250 ° C, more preferably 170 to 230 ° C. When the resin temperature becomes too high, the polyvinyl acetal resin is decomposed and the content of volatile substances is increased. On the other hand, when the temperature is too low, the content of volatile substances increases. In order to efficiently remove the volatile substance, it is preferable to remove the volatile substance from the vent port of the extruder by reducing the pressure. When the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) is produced using an extruder, the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) may be melt-extruded on the metal foil as described later. Good.

The thickness of the polyvinyl acetal layer (1) is preferably 8 μm or more, more preferably 20 μm or more, and further preferably 30 μm or more. When the thickness of the polyvinyl acetal layer (1) is equal to or more than the above value, a problem that distortion or the like occurs in the conductive structure due to contraction or deformation of the sheet (A) hardly occurs. The thickness of the polyvinyl acetal layer (1) is preferably 800 μm or less, more preferably 700 μm or less, and particularly preferably 600 μm or less. When the polyvinyl acetal layer (1) is not more than the above value, when the sheet (A) is wound around the core to form a roll, defects such as wrinkles are formed on the surface of the sheet (A) near the core. It is difficult to occur or a defect such as a crack is generated on the surface of the sheet (A) far from the core. The thickness of the polyvinyl acetal layer (1) is measured using a thickness meter or a laser microscope.

The thickness of the polyvinyl acetal layer (2) is preferably 100 μm or more, more preferably 200 μm or more, and further preferably 300 μm or more. When the thickness of the polyvinyl acetal layer (2) is equal to or more than the above value, it is easier to obtain a laminated glass having the safety required for a safety laminated glass. The thickness of the polyvinyl acetal layer (2) is preferably 1100 μm or less, more preferably 1000 μm or less, and particularly preferably 900 μm or less. When the thickness of the polyvinyl acetal layer (2) is equal to or less than the above value, when the sheet (A) is wound around the core to form a roll, the surface of the sheet (A) near the core is wrinkled. And defects such as cracks are unlikely to occur on the surface of the sheet (A) far from the core. The thickness of the polyvinyl acetal layer (2) is measured using a thickness meter or a laser microscope.

In a preferred embodiment, the degree of polymerization of the polyvinyl acetal (1) is smaller than the degree of polymerization of the polyvinyl acetal (2), and the thickness of the polyvinyl acetal layer (1) is smaller than the thickness of the polyvinyl acetal layer (2). In this aspect, when the sheet (A) in the present invention is used as an interlayer film for laminated glass, it is preferable because the transition of the plasticizer between layers easily proceeds when producing the laminated glass.

In a preferred embodiment, the temperature at which tan δ of the composition constituting the polyvinyl acetal layer (1) takes a maximum value is Tg ₁ , and the temperature at which tan δ of the composition constituting the polyvinyl acetal layer (2) takes a maximum value is Tg _2. In this case, at least one of Tg ₁ and Tg ₂ is 5 ° C. or higher. At least one of Tg ₁ and Tg ₂ is more preferably 15 ° C. or higher, and particularly preferably 20 ° C. or higher. Tg ₁ and Tg ₂ can be adjusted by the kind of resin and the kind and amount of the plasticizer contained in the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2). When at least one of Tg ₁ and Tg ₂ is equal to or greater than the above lower limit, the sheets (A) are less likely to adhere to each other, and defects such as breakage, peeling, and disconnection in the conductive structure are less likely to occur during the production of laminated glass. Tg ₁ and Tg ₂ are obtained from the peak temperature of tan δ in the dynamic viscoelasticity measurement.

For the bonding surface of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) with the conductive structure or another functional layer described later, the average surface roughness Rz value is preferably 20 μm or less, more preferably 5 μm or less. Particularly preferably, it is 3 μm or less, and the average length RSm value of the roughness curve element is preferably 500 μm or more, more preferably 1000 μm or more, and particularly preferably 1300 μm or more. When the Rz value is equal to or less than the above value and the RSm value is equal to or greater than the above value, uniform printing or coating is possible, and bonding with ink or metal foil or another functional layer, which is a material constituting the conductive structure. Sexual irregularities are easily suppressed. The Rz value and the RSm value are measured according to JIS B0601-1994 using a surface roughness meter or a laser microscope. As a method for adjusting the Rz value to be lower than the above value and the RSm value to be higher than the above value, a melt extrusion method (for example, a method using a T die, a method for performing inflation molding, or the like), a solvent casting method, or the like is employed. . It is preferable to form the melt extruded from the T-die with a smooth cooling roll. Moreover, in order to form a smoother surface, it is more preferable to use a metal elastic roll.

<Conductive structure>
The sheet | seat (A) in this invention is equipped with the electrically conductive structure arrange | positioned between a polyvinyl acetal layer (1) and a polyvinyl acetal layer (2).

The thickness of the conductive structure is preferably 1 to 30 μm, more preferably 2 to 15 μm, and particularly preferably 3 to 10 μm from the viewpoints of electrical resistance and ease of manufacture. The thickness of the conductive structure is measured using a thickness meter or a laser microscope.

The conductive structure preferably has a linear shape, a lattice shape, or a net shape from the viewpoints of electrical resistance, heat generation performance, electromagnetic wave absorption, optical characteristics, and the like. Here, examples of the line shape include a straight line shape, a wavy line shape, and a zigzag shape. In one conductive structure, the shape may be single, or a plurality of shapes may be mixed.

In one aspect, the conductive structure is a heat generating conductive structure.

In some embodiments, for example, in which a conductive structure is formed by a printing method and, for example, the laminated glass is partially heated or used as a sensor or antenna in a region where it is not important to ensure forward visibility, a sufficient amount of heat is generated. Alternatively, from the viewpoint of ensuring functionality as a sensor or antenna and ease of manufacture, the conductive structure is preferably composed of a plurality of linear conductive materials having a line width of 0.01 to 5 mm. That is, the line width of the linear conductive material (wiring) constituting the above-described linear, grid or net shape is preferably 0.01 to 5 mm. The line width is more preferably 0.02 to 2 mm, particularly preferably 0.03 to 1 mm.

In another embodiment, for example, an embodiment in which the laminated glass is entirely heated, the conductive structure has a plurality of linear conductors having a line width of 1 to 30 μm from the viewpoint of easily ensuring both a sufficient calorific value and good forward visibility. It is preferable that it is comprised with the property material. That is, the line width of the linear conductive material constituting the above-described linear, grid or net shape is preferably 1 to 30 μm. The line width is more preferably 2 to 15 μm, particularly preferably 3 to 12 μm.

The conductive material forming the conductive structure is preferably silver or copper from the viewpoints of ensuring electrical resistance or heat generation and ease of manufacture, and more preferably copper from an economic viewpoint.

It is preferable that at least one surface of the conductive structure is processed with low reflectance, and it is more preferable that the entire surface of the conductive structure is processed with low reflectance. In the present invention, “low reflectance treatment” means that the visible light reflectance measured according to JIS R 3106 is 30% or less. From the viewpoint of forward visibility, it is more preferable that the visible light reflectance is 10% or less. When the visible light reflectance is less than or equal to the above upper limit value, when a laminated glass is produced by laminating a polyvinyl acetal layer (1) having a conductive structure and a polyvinyl acetal layer (2) as described later, a desired glass is produced. Visible light reflectance is easy to obtain, and when laminated glass is produced, the forward visibility tends to be excellent.

Examples of the low reflectance treatment method include blackening treatment (darkening treatment), browning treatment, and plating treatment. From the viewpoint of process passability, the low reflectance treatment is preferably a blackening treatment. Therefore, from the viewpoint of good forward visibility, it is particularly preferable that one surface, both surfaces, or the entire surface of the conductive structure is blackened so that the visible light reflectance is 10% or less. Specifically, the blackening treatment is performed using an alkaline blackening solution or the like.

<Another functional layer>
The sheet (A) in the present invention may have one or more other functional layers in addition to the conductive structure between the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2). When the sheet (A) has another functional layer, the other functional layer is between the polyvinyl acetal layer (1) and the conductive structure and / or between the polyvinyl acetal layer (2) and the conductive structure. Exists. As another functional layer, for example, an infrared reflection layer, an ultraviolet reflection layer, a color correction layer, an infrared absorption layer, an ultraviolet absorption layer, a fluorescent / light emitting layer, a sound insulation layer, an electrochromic layer, a thermochromic layer, a photochromic layer, a design An elastic layer or a high elastic modulus layer. The thickness of the other functional layer is not particularly limited, and may be set as appropriate according to the desired function.

<Method for producing sheet (A)>
The sheet (A), for example, imparts a conductive structure to the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2), and optionally another functional layer and the remaining polyvinyl acetal layer are provided on the conductive structure side. It can be manufactured by bonding.

There is no particular limitation on the method for applying the conductive structure to the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2). And a method of coating, printing or laminating the material constituting the material.

The method for coating, printing or laminating the material is not particularly limited.
As a method of coating the material, for example, a method of coating a conductive structure with a melt of a resin composition constituting the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) (for example, the method described above on a conductive structure) A method of melt-extruding the resin composition, or a method of applying the resin composition onto the conductive structure by knife coating or the like); or vapor deposition, sputtering or electro-deposition on the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) And a method for providing a conductive structure.
Examples of the method for printing the material include screen printing, flexographic printing, and gravure printing. In the printing method, an ink that is dried or cured by heat or light is used before laminating the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) having a conductive structure.
As a method of laminating the material, for example, a method in which a conductive structure and a polyvinyl acetal layer (1) or a polyvinyl acetal layer (2) are stacked and thermocompression bonded; a solvent, a polyvinyl acetal layer (1) or a polyvinyl acetal layer (2) A resin composition solution containing a resin and a solvent is applied to one or both of the conductive structure and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2), or the conductive structure and polyvinyl. A method of injecting between the acetal layer (1) or the polyvinyl acetal layer (2) and joining the conductive structure and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2); the conductive structure and polyvinyl with an adhesive Bonded with acetal layer (1) or polyvinyl acetal layer (2) That method; and the like.

Therefore, in one aspect, the multilayer structure of the present invention has an adhesive layer between at least one of the polyvinyl acetal layer (1) and the conductive structure and between the polyvinyl acetal layer (2) and the conductive structure. You may have. The adhesive to be used must be one that does not hinder the transparency of the sheet (A) to be obtained. For example, it is preferable to use polyvinyl acetal, acrylic or urethane having a low polymerization degree.

From the viewpoint that haze derived from the adhesive for bonding the conductive structure cannot be generated, the sheet (A) in the present invention is formed between the polyvinyl acetal layer (1) and the conductive structure, and the polyvinyl acetal layer ( It is preferable not to have an adhesive layer between 2) and the conductive structure. In this aspect, it is easy to obtain better transparency of the sheet (A) in the present invention, and it is easier to obtain better transparency when a laminated glass is produced using the sheet (A).

The ink used in the printing method includes conductive particles and / or conductive fibers. The conductive particles or conductive fibers are not particularly limited, for example, metal particles (for example, gold, silver, copper, zinc, iron or aluminum particles); metal-coated particles or fibers (for example, silver-plated glass fibers or Glass spheres); or particles or fibers of conductive carbon black, carbon nanotubes, graphite or graphene; and the like. Further, the conductive particles may be semiconductor particles such as conductive metal oxide particles, such as particles of indium doped tin oxide, indium doped zinc oxide or antimony doped tin oxide. The ink preferably contains silver particles, copper particles and / or carbon nanotubes from the viewpoint of conductivity, more preferably contains silver particles or copper particles, and particularly contains copper particles from an economic viewpoint. preferable.

From the viewpoint of high production efficiency when applying the conductive structure and easy blackening treatment, the conductive structure is preferably a metal foil etching structure. The method of joining the metal foil and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) is performed by, for example, the following methods (I) to (III).
(I) A method in which the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) and a metal foil are laminated and thermocompression bonded,
(II) A method of coating and joining the melt of the resin composition constituting the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) on the metal foil, for example, melt extrusion of the resin composition on the metal foil Or a method of applying the resin composition on a metal foil by knife coating or the like, or (III) a solvent, a resin constituting the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) and a resin containing the solvent The solution or dispersion of the composition is applied to one or both of the metal foil and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2), or the metal foil and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2 Between the metal foil and the polyvinyl acetal layer (1) or polyvinyl acetal. (2) a method for bonding.

The metal foil and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) may be bonded with an adhesive, but as described above, the adhesive inhibits the transparency of the obtained sheet (A). Must not be. Moreover, as described above, from the viewpoint that haze derived from an adhesive cannot be generated, the metal foil and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) can be joined without using an adhesive. preferable.

The bonding temperature when thermocompression bonding the metal foil and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) in the method (I) is a resin constituting the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2). Depending on the type, the temperature is usually 90 to 170 ° C., preferably 100 to 160 ° C., more preferably 110 to 155 ° C., and still more preferably 110 to 150 ° C. When the bonding temperature is within the above range, it is easy to obtain good bonding strength.

The resin temperature at the time of extrusion in the above method (II) is preferably 150 to 250 ° C. from the viewpoint of reducing the content of volatile substances in the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2), and is preferably 170 to 230 ° C is more preferred.

As the solvent in the above method (III), it is preferable to use a plasticizer usually used for polyvinyl acetal resins. As such a plasticizer, those described in the paragraph of <Plasticizer> above are used.

The step of forming a desired shape of the conductive structure from the obtained polyvinyl acetal layer with metal foil (1) or the polyvinyl acetal layer with metal foil (2) is carried out using a known photolithography technique. In the process, for example, as described in the following examples, a dry film resist is first laminated on the metal foil of the polyvinyl acetal layer (1) with metal foil, and then an etching resistance pattern is formed using a photolithography technique. Then, after the polyvinyl acetal layer (1) provided with the etching resistance pattern is immersed in a copper etching solution to form the shape of the conductive structure, the remaining photoresist layer is removed by a known method. The

In a preferred embodiment, at least one surface of the conductive structure is subjected to a low reflectance treatment. This embodiment is achieved, for example, by using a metal foil in which at least one surface is subjected to a low reflectance treatment. Further, the low reflectance treatment may be performed after the shape of the conductive structure is formed by the photolithography method described above. The low reflectance treatment of the metal foil and the conductive structure can be performed using an alkaline blackening solution or the like as described above.

The metal foil preferably contains silver or copper, and more preferably contains copper from an economical viewpoint, from the viewpoints of ensuring electrical resistance or heat generation and manufacturing ease. In a particularly preferred embodiment, the metal foil is a copper foil.

Next, on the surface having the conductive structure of the obtained polyvinyl acetal layer with conductive structure (1) or polyvinyl acetal layer with conductive structure (2), another polyvinyl acetal layer [ie, polyvinyl with conductive structure] In the case of the acetal layer (1), the polyvinyl acetal layer (2), and in the case of the polyvinyl acetal layer with a conductive structure (2), the polyvinyl acetal layer (1)] is bonded to produce the sheet (A). This joining method may be the same method as the method for joining the metal foil and the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) described above.

When the sheet (A) in the present invention has another functional layer in addition to the conductive structure between the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2), The method for applying the acetal layer (1), the polyvinyl acetal layer (2), the polyvinyl acetal layer with a conductive structure (1) or the polyvinyl acetal layer with a conductive structure (2) is the same as that described above. The same method as that applied to the acetal layer (1) or the polyvinyl acetal layer (2) may be used. Moreover, as another method, when another functional layer consists of a resin composition, a functional layer different from the resin composition constituting the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) is constituted. The method of extruding simultaneously with a resin composition; Or the method of dipping a polyvinyl acetal layer (1) or a polyvinyl acetal layer (2) in the solution of the resin composition which comprises another functional layer is mentioned.

The thickness of the sheet (A) is preferably 20 μm or more, more preferably 80 μm or more, further preferably 150 μm or more, still more preferably 350 μm or more, and particularly preferably 700 μm or more. When the thickness of the sheet (A) is equal to or greater than the above value, the problem that the conductive structure is distorted due to the contraction or deformation of the sheet (A) hardly occurs. When used as a membrane, excellent penetration resistance is easily exhibited. Further, the thickness of the sheet (A) is preferably 1700 μm or less, more preferably 1200 μm or less, and particularly preferably 900 μm or less. When the thickness of the sheet (A) is not more than the above value, when the amount of plasticizer contained in the polyvinyl acetal layer (1) and the amount of plasticizer contained in the polyvinyl acetal layer (2) are different, more plasticizers The amount of plasticizer transferred from the polyvinyl acetal layer containing the amount of plasticizer to the polyvinyl acetal layer containing less plasticizer amount is reduced, and the decrease in the amount of plasticizer in the polyvinyl acetal layer containing more plasticizer amount is suppressed, Problems such as a large head impact at the time of collision of a vehicle on which the vehicle glass using the sheet (A) is mounted are unlikely to occur. The thickness of the sheet (A) is measured using a thickness meter or a laser microscope.

In a preferred embodiment, the sheet (A) has a concavo-convex structure on at least one surface thereof. The surface having the concavo-convex structure of the sheet (A) may be any surface on the polyvinyl acetal layer (1) side and the polyvinyl acetal layer (2) side. The average surface roughness Rz value of the surface having the concavo-convex structure is preferably 15 to 70 μm, more preferably 20 to 50 μm, and the average length RSm value of the roughness curve element is preferably 100 to 1000 μm, more preferably 300 to 700 μm. When the sheet (A) has a concavo-convex structure on at least one surface thereof (particularly, when the average surface roughness Rz value of at least one surface of the sheet (A) satisfies the above range), the multilayer structure of the present invention Sheets (A) are less likely to adhere to each other, and defects such as breakage, peeling, and disconnection in the conductive structure are less likely to occur during laminated glass production. The Rz value and the RSm value are measured according to JIS B0601-1994 using a surface roughness meter or a laser microscope. The concavo-convex structure can be imparted, for example, by embossing the sheet (A) or the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) before imparting the conductive structure between at least one roll pair. The desired average surface roughness Rz value and the average length RSm value of the roughness curve element can be adjusted.

In a preferred embodiment, two sheets (A) are stacked such that the surface on the polyvinyl acetal layer (1) side and the surface on the polyvinyl acetal layer (2) side are in contact with each other, and perpendicular to the surface at 23 ° C. and 50% RH. The peeling force showing the blocking resistance after applying a pressure of 0.02 MPa for 48 hours in any direction is 30 N / 30 mm or less. The peeling force is more preferably 15 N / 30 mm or less, and particularly preferably 10 N / 30 mm or less. When the peeling force is less than or equal to the above upper limit value, the sheets (A) are more difficult to adhere to each other in the multilayer structure of the present invention, and defects such as breakage, peeling and disconnection in the conductive structure are less likely to occur during laminated glass production. . The said peeling force can be adjusted with the uneven | corrugated structure of the kind of resin contained in a polyvinyl acetal layer (1) and a polyvinyl acetal layer (2), the kind and quantity of a plasticizer, and a sheet | seat (A) surface. The lower limit of the peeling force is 0 N / 30 mm.

The multilayer structure of the present invention is a multilayer structure in which two or more sheets (A) overlap each other, and can be used when producing laminated glass. The multilayer structure of the present invention is suitable for storage or transportation because it is in a state in which two or more sheets are rolled and overlapped, or is cut out to a certain size and stacked in two or more. When producing laminated glass using a sheet (A), for example, when unwinding a sheet (A) from a roll, when taking out two or more sheets (A) one by one, and for producing laminated glass In addition, when joining to a transparent substrate, the workability is excellent, and defects such as breakage, peeling or disconnection of the conductive structure are extremely unlikely to occur. Moreover, when a laminated glass is produced using the sheet (A) in the present invention, a laminated glass having both transparency and performance (safety) as a safety laminated glass is produced. In a sheet that is easy to adhere between sheets, it is possible to prevent the sheet from adhering by interposing a protective film between the sheets so that the above defects do not occur. This causes a problem of increasing waste. In the multilayer structure of the present invention, the above defects in the conductive structure are very unlikely to occur even if a protective film is not interposed between the sheets (A).

In one embodiment, the sheet (A) is wound on a winding core in the multilayer structure formed in a roll shape of the present invention. In the wound sheet (A), either the polyvinyl acetal layer (1) or the polyvinyl acetal layer (2) may be inside. The diameter of the winding core is usually 20 mm or more, preferably 50 mm or more. The diameter of the winding core is usually 500 mm or less. When the diameter of the winding core is within the above range, problems such as distortion of the conductive structure due to deformation of the sheet (A) and wrinkles and cracks on the surface of the sheet (A) occur. It is difficult to obtain good productivity. A method for winding the sheet (A) on the core is not particularly limited, and a method usually used as a method for winding the sheet on the core can be adopted.

<Laminated glass>
The laminated glass which has a sheet | seat (A) between several transparent base materials can be manufactured using the sheet | seat (A) in this invention.

Each wiring of the conductive structure in the laminated glass is connected to the bus bar. As the bus bar, a bus bar usually used in the art is used, and examples thereof include a metal foil tape, a metal foil tape with a conductive adhesive, and a conductive paste. Also, the bus bar may be formed by printing the bus bar at the same time when forming the conductive structure or leaving a part of the metal foil as the bus bar. A power supply line is connected to each bus bar, and each power supply line is connected to a power source, so that a current is supplied to the conductive structure.

In one aspect, in the multilayer structure of the present invention, the sheet (A) has a terminal for receiving electric power or an electric signal arranged so as to protrude outward. As the terminal, a terminal normally used in this technical field is used.

From the viewpoint of transparency, weather resistance and mechanical strength, the transparent substrate is preferably an inorganic glass (hereinafter sometimes simply referred to as glass), a methacrylic resin sheet, a polycarbonate resin sheet, a polystyrene resin sheet, or a polyester resin. An organic glass such as a resin sheet or a polycycloolefin-based resin sheet, more preferably an inorganic glass, a methacrylic resin sheet, or a polycarbonate resin sheet, and particularly preferably an inorganic glass. The inorganic glass is not particularly limited, and examples thereof include float glass, tempered glass, semi-tempered glass, chemically tempered glass, green glass, and quartz glass.

In particular, when the seat (A) of the present invention is used in a vehicle glass, particularly a vehicle windshield, the surface of the conductive structure subjected to the low reflectance treatment comes to the passenger side from the viewpoint of forward visibility. It is preferable to arrange the sheet (A). Moreover, since there exists a possibility that a water | moisture content may penetrate | invade from a laminated glass edge part and cause a corrosion of a conductive structure, it is preferable that the conductive structure is arrange | positioned 1 cm or more inside from the edge part of a laminated glass.

<Interlayer film for laminated glass (C)>
The laminated glass manufactured using the sheet (A) in the present invention has safety required for safety laminated glass. On the other hand, from the viewpoint of imparting further penetration resistance, the laminated glass may further include one or more interlayer films for laminated glass (C) between a plurality of transparent substrates, but the production efficiency. From the viewpoint of lowering, it is preferable not to have the interlayer film for laminated glass (C). When the laminated glass has an interlayer film for laminated glass (C), the interlayer film for laminated glass (C) may be in contact with the polyvinyl acetal layer (1) or may be in contact with the polyvinyl acetal layer (2). Good. The interlayer film for laminated glass (C) is not particularly limited, and a conventionally used interlayer film for laminated glass can be used. For example, a plasticized polyvinyl acetal resin layer comprising a polyvinyl acetal resin and a plasticizer Is mentioned. The polyvinyl acetal resin may be, for example, the polyvinyl acetal resin described in the paragraph of <Polyvinyl Acetal (1) and Polyvinyl Acetal (2)> and can be produced by the same method as that described in the same paragraph.

The plasticizer content in the interlayer film for laminated glass (C) is preferably relative to 100 parts by mass of the resin in the resin composition constituting the interlayer film for laminated glass (C) in the initial state before lamination of the layers. 19 parts by mass or more, more preferably 19 to 56 parts by mass, still more preferably 28 to 47 parts by mass, and particularly preferably 35 to 43 parts by mass. When the content of the plasticizer is within the above range, it is easy to obtain a laminated glass excellent in impact resistance. Moreover, the plasticized polyvinyl acetal resin layer which has a sound-insulation function can also be used as an intermediate film (C) for laminated glass. In that case, the content of the plasticizer is preferably 42 parts by mass or more with respect to 100 parts by mass of the resin in the resin composition constituting the interlayer film for laminated glass (C) in the initial state before the layers are laminated. The amount is preferably 42 to 100 parts by mass, more preferably 45 to 67 parts by mass, and particularly preferably 47 to 54 parts by mass. As the plasticizer, the plasticizers described in the preceding <Plasticizer> paragraph can be used.

The interlayer film for laminated glass (C) may contain the additive described in the previous <Additive> paragraph, if necessary.

The interlayer film for laminated glass (C) can be produced by the method described in the above paragraph <Method for producing polyvinyl acetal layer (1) and polyvinyl acetal layer (2)>.

The thickness of the interlayer film for laminated glass (C) is preferably 100 to 1600 μm, more preferably 350 to 1200 μm, and still more preferably 700 to 900 μm. It is easy to obtain excellent penetration resistance when the thickness of the interlayer film for laminated glass (C) is not less than the above value. The thickness is measured using a thickness meter or a laser microscope.

When the laminated glass has an interlayer film for laminated glass (C), the amount of hydroxyl groups of the polyvinyl acetal resin constituting the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) and the interlayer film for laminated glass (C) are configured. The difference from the amount of hydroxyl groups in the polyvinyl acetal resin is preferably 5 mol% or less, more preferably 3 mol% or less, and particularly preferably 1 mol% or less. When the polyvinyl acetal resin constituting the polyvinyl acetal (1), the polyvinyl acetal (2), or the interlayer film for laminated glass (C) is composed of a mixture of a plurality of resins, the average hydroxyl amount of the polyvinyl acetal (1), the polyvinyl acetal ( It is preferable that the average hydroxyl group content of 2) or the average hydroxyl group content of the polyvinyl acetal resin constituting the interlayer film for laminated glass (C) satisfies the above relationship. When the difference is less than or equal to the upper limit, the refractive index of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) and the interlayer film for laminated glass (C) in an equilibrium state after the plasticizer is transferred in the laminated glass Since the difference is small, when the interlayer film for laminated glass (C), the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) having different dimensions are used, the boundary is difficult to visually recognize, or the sheet (A) And the interface with the interlayer film for laminated glass (C) is difficult to visually recognize.
On the other hand, the plasticizer migrated by making a difference between the amount of hydroxyl groups of the polyvinyl acetal (1) and / or polyvinyl acetal (2) and the amount of hydroxyl groups of the polyvinyl acetal resin constituting the interlayer film for laminated glass (C). Between the amount of plasticizer in the polyvinyl acetal layer (1) and the amount of plasticizer in the interlayer film for laminated glass (C) in the equilibrium state and / or the amount of plasticizer in the polyvinyl acetal layer (2) and the intermediate for laminated glass It is also possible to obtain a laminated glass having excellent sound insulation performance by making a difference with the amount of plasticizer in the film (C). In that case, the difference in the amount of the hydroxyl group is preferably 5 mol% or more, more preferably 8 mol% or more.

The laminated glass has the functional layer described in <Other functional layer> in addition to the sheet (A) and optionally the interlayer film for laminated glass (C) between a plurality of transparent substrates. In that case, the other functional layer may be in contact with any of the polyvinyl acetal layer (1), the polyvinyl acetal layer (2), and, if present, the interlayer film for laminated glass (C).

<Method for producing laminated glass>
Laminated glass can be produced by methods known to those skilled in the art. For example, an arbitrary number of sheets (A) and optionally an interlayer film for laminated glass (C) and / or another functional layer are arranged in any order on a transparent substrate, and another transparent group As a pre-compression process, the laminated material is heated to increase the temperature of the sheet (A) and optionally the laminated glass interlayer film (C) and / or another functional layer on the transparent substrate entirely or locally. Laminated glass can be produced by applying it and then processing in an autoclave.

In addition, the sheet (A) and optionally the interlayer film for laminated glass (C) and / or another functional layer are preliminarily pressure-bonded and placed between two transparent substrates to be fused to each other at a high temperature. By doing so, laminated glass may be manufactured.

As the pre-pressing step, from the viewpoint of removing excess air or performing light joining between adjacent layers, a method of degassing under reduced pressure by a method such as a vacuum bag, a vacuum ring, or a vacuum laminator, Examples thereof include a method of deaeration using a nip roll and a method of compression molding at a high temperature. For example, the vacuum bag method or the vacuum ring method described in EP 1235683 B1 is carried out at about 2 × 10 ⁴ Pa and 130 to 145 ° C., for example. A vacuum laminator consists of a heatable and vacuumable chamber in which laminated glass is formed within a time period of about 20 minutes to about 60 minutes. Usually, a reduced pressure of 1 Pa to 3 × 10 ⁴ Pa and a temperature of 100 ° C. to 200 ° C., particularly 130 ° C. to 160 ° C. are effective. When using a vacuum laminator, the treatment in the autoclave may not be performed depending on the temperature and pressure.

The treatment in the autoclave is performed, for example, at a pressure of about 1 × 10 ⁶ Pa to about 1.5 × 10 ⁶ Pa and a temperature of about 100 ° C. to about 145 ° C. for about 20 minutes to 2 hours.

The method of disposing the sheet (A) and optionally the interlayer film for laminated glass (C) and / or another functional layer on the first transparent substrate is not particularly limited, and various methods are applied. For example, the sheet (A) and, optionally, the interlayer film for laminated glass (C) and / or another functional layer may be supplied from a roll having a suitable width and then cut to a desired size. And you may arrange | position the film cut | disconnected in the target magnitude | size beforehand. For example, in the case of an automobile windshield, a sheet (A) supplied from a roll and optionally an interlayer film for laminated glass (C) may be joined, heated / stretched, cut and processed into a fan shape.

In the automotive field, particularly when producing a windshield, the upper part of the glass may have a so-called color shade region. Therefore, the sheet (A) and / or the interlayer film for laminated glass (C) are extruded together with the correspondingly colored polymer melt, or the sheet (A) and the interlayer film for laminated glass (C). At least one of them may have a partially different coloration. Therefore, the sheet (A) and / or the interlayer film for laminated glass (C) may have a color gradation adapted to the shape of the windshield.

The interlayer film for laminated glass (C) may have a wedge-shaped thickness profile. At this time, the laminated glass can have a wedge-shaped thickness profile even when the thickness profile of the sheet (A) is a parallel plane, and can be used for a head-up display (HUD) in an automobile windshield.

The interlayer film for laminated glass (C) may be a commercially available plasticized polyvinyl butyral sheet, the interlayer film for laminated glass (C) in which nanoparticles having infrared absorbing ability or reflectivity are dispersed, and colored laminated glass The interlayer film for laminated glass (C) or the interlayer film for laminated glass (C) having a sound insulating function may be used.

Laminated glass can be used as laminated glass in buildings or vehicles. Laminated glass in a vehicle means a windshield, a rear glass, a roof glass, a side glass, or the like for a vehicle such as a train, a train, an automobile, a ship, or an aircraft.

The haze when light is irradiated from the low-reflectance-treated surface (for example, blackened surface) side of the laminated glass produced using the sheet (A) in the present invention is usually 2.0 or less, preferably 1. It is 8 or less, more preferably 1.5 or less. The haze when light is irradiated from the metallic gloss surface side of the laminated glass produced using the sheet (A) in the present invention is usually 3.0 or less, preferably 2.8 or less, more preferably 2.5. It is as follows. The haze is measured according to JIS R 3106. By using the sheet (A) in which the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) contain a specific resin and a specific amount of a plasticizer, the haze is reduced by reducing the line width of the conductive structure. It can be adjusted below the upper limit.

In the laminated glass produced using the sheet (A) in the present invention, the plasticizer contained in the polyvinyl acetal layer (1), the plasticizer contained in the polyvinyl acetal layer (2), and / or the laminated glass optionally present. The plasticizer contained in the interlayer film (C) for use moves to other layers as time passes, and the amount of plasticizer contained in the interlayer film for laminated glass (C) when present in each layer and in the equilibrium state is The same level. The amount of plasticizer (average plasticizer amount) at this time is preferably 18 to 35% by mass, more preferably 20 to 30% by mass, and particularly preferably 25 to 29% by mass. When the average plasticizer amount is within the above range, for example, it is easy to obtain the desired characteristics in the laminated glass, for example, the impact on the head of the rider at the time of collision is reduced. The average plasticizer amount is calculated by the following method.

A (mass%): amount of plasticizer of interlayer film for laminated glass (C) a (mm): thickness of interlayer film for laminated glass (C) B (mass%): amount of plasticizer of polyvinyl acetal layer (1) b (mm): thickness of polyvinyl acetal layer (1) C (mass%): amount of plasticizer of polyvinyl acetal layer (2) c (mm): thickness of polyvinyl acetal layer (2) a to c and A By adjusting the value of ~ C, the average plasticizer amount can be adjusted within the above range.

Since the sheet (A) in the present invention is excellent in transparency, the laminated glass produced using the sheet (A) in the present invention is also excellent in transparency. Further, when the sheet (A) is used for producing a laminated glass, defects such as breakage, peeling and disconnection in the conductive structure are extremely difficult to be produced, and the workability is excellent. In addition to the sheet (A), an interlayer film for laminated glass Even if it is not used, the laminated glass provided with the safety | security required for the safety laminated glass is brought about. Therefore, the multilayer structure of the present invention is suitable for producing laminated glass.

[Example 1]
Polyvinyl butyral resin PVB-1 shown in Table 1 was melt-kneaded, and the resulting melt-kneaded product was extruded into a strand shape and pelletized. The obtained pellet was melt-extruded using a single screw extruder and a T die, and a 50 μm thick polyvinyl acetal layer (1) was obtained using a metal elastic roll. Further, polyvinyl butyral resin PVB-2 (100 parts by mass) shown in Table 1, triethylene glycol-bis- (2-ethylhexanoate) (hereinafter referred to as “3G8”) and di (butoxyethyl) adipate 40 parts by mass of a mixture (hereinafter referred to as “DBEA”) (mass ratio 10/1) is melt-kneaded to produce a sheet having a thickness of 800 μm in the same manner as the polyvinyl acetal layer (1). A concave-convex structure was formed so that the ten-point average surface roughness Rz was 35 μm to obtain a polyvinyl acetal layer (2). On the obtained polyvinyl acetal layer (1), a copper foil having a thickness of 7 μm, which was blackened on one side, was overlapped so that the blackened surface and the polyvinyl acetal layer (1) were in contact with each other. Here, the visible light reflectance of the blackened surface measured according to JIS R 3106 was 5.2%. Next, the upper and lower sides of the laminate in which the polyvinyl acetal resin layer (1) and the copper foil are stacked are sandwiched between PET films having a thickness of 50 μm and passed between thermocompression-bonding rolls set at 120 ° C. (pressure: 0.2 MPa, After a speed of 0.5 m / min), the PET film was peeled off. Next, after laminating a dry film resist on the copper foil, an etching resistance pattern was formed using a photolithography technique. Next, after immersing in a copper etching solution to form a conductive structure, the remaining photoresist layer was removed by a conventional method to obtain a polyvinyl acetal layer (1) having a conductive structure. The conductive structure has a copper mesh structure in which copper wires having a line width of 10 μm are arranged in a lattice pattern at intervals of 500 μm, and the upper and lower sides thereof are connected to a copper wire structure having a width of 5 mm corresponding to a bus bar. It was. Next, the polyvinyl acetal layer (2) was laminated on the obtained conductive structure so that the surface on which the uneven structure was not formed was in contact with the conductive structure, and was laminated to obtain a sheet (A). The following evaluation was performed on the sheet (A). The results are shown in Table 2.

[Ten point average surface roughness Rz]
About each of the polyvinyl acetal layer (1) side and the polyvinyl acetal layer (2) side of the sheet (A), the surface roughness was measured with a surface roughness meter, and the ten-point average surface roughness was determined. In Table 2, “None” is described when the ten-point average roughness is less than 5 μm, and the numerical value is described when it is 5 μm or more.

[Peeling force showing blocking resistance]
Two samples having a size of 3 cm × 10 cm were cut out from the sheet (A), and stacked so that the polyvinyl acetal layer (1) of one sheet (A) was in contact with the polyvinyl acetal layer (2) of the other sheet (A). This was placed on a flat desk, a load was placed on it, and it was allowed to stand at 23 ° C. and 50% RH so that a pressure of 0.02 MPa was applied in a direction perpendicular to the 3 cm × 10 cm surface. After 48 hours, the adhesive strength between the sheets (A) at 23 ° C. and 50% RH was measured by a T-shaped peel test (using Shimadzu Autograph SI, speed 500 mm / min), and the maximum peel force obtained. Was defined as a peeling force showing blocking resistance. The same test was performed 5 times, and the average value was obtained.

[Tg ₁ , Tg ₂ ]
The composition constituting the polyvinyl acetal layer (1) and the composition constituting the polyvinyl acetal layer (2) were respectively press-molded at 150 ° C. and 100 kg / cm ² for 30 minutes to obtain a sheet having a thickness of 0.8 mm. . The obtained sheet was cut into a width of 3 mm to obtain a dynamic viscoelasticity measurement sample. For this measurement sample, a dynamic viscoelasticity device (Rheogel-E4000 manufactured by UBM Co., Ltd.) was used and the temperature was increased from −50 to 100 ° C. at 3 ° C./min. The analysis was performed in 3 Hz, displacement 75.9 μm, automatic static load 26 g, and tensile mode. The temperatures at which tan δ of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) were maximized were defined as Tg ₁ and Tg ₂ , respectively.

[Roll pull-out test]
A sheet (A) 10 m was wound around a core having a diameter of 7.5 cm and stored at 23 ° C. and 50% RH for 2 days. The sheet (A) after storage was pulled out at a speed of 10 cm / second, the conductive structure was visually confirmed, and the following three items were evaluated.
(I) Damage to the conductive structure The sheet (A) after drawing was visually evaluated, and “no” was given when no breakage or peeling was confirmed, and “Yes” was given when breakage or peeling was confirmed. .
(Ii) Generation of wrinkle The sheet (A) after drawing was visually evaluated, and “no” was given when the surface did not have wrinkles, and “existed” when the surface was wrinkled.
(Iii) Self-adhesiveness The presence or absence of self-adhesiveness was evaluated, and evaluated according to the following criteria.
A: Self-adhesion was not seen.
B: Self-attached, but peelable without deformation of the sheet (A).
C: Self-attached, and the sheet (A) was deformed when peeled.
D: Self-attached, and sheet (A) was significantly deformed or damaged when peeled.

[Sheet (A) tan δ peak temperature measurement after high temperature treatment]
The sheet (A) is cut into a size of 10 cm long × 10 cm wide, sandwiched between two PET films (vertical 10 cm × width 10 cm × thickness 0.1 mm), and further, two pieces of length 10 cm, width 10 cm, thickness 3 mm. Sandwiched between glasses. Subsequently, this was put in a vacuum bag and reduced in pressure for 15 minutes at room temperature using a vacuum pump. Then, the temperature was raised to 100 ° C. while reducing the pressure, and the mixture was heated as it was for 60 minutes. After cooling, the pressure was returned to normal pressure. Thereafter, this was put into an autoclave and treated at 140 ° C. and 1.2 MPa for 30 minutes. The glass and the PET film were removed to obtain a sheet. The obtained sheet was cut into a width of 3 mm to obtain a dynamic viscoelasticity measurement sample. For this measurement sample, a dynamic viscoelasticity device (Rheogel-E4000 manufactured by UBM Co., Ltd.) was used and the temperature was increased from −50 to 100 ° C. at 3 ° C./min. Analysis was performed at 3 Hz, displacement 75.9 μm, automatic static load 26 g, and tensile mode, and the temperature at which tan δ was maximized was measured and evaluated according to the following criteria. From the viewpoint of safety expression when the sheet (A) is used as an interlayer film for laminated glass, A and B are preferable in this order, and C is not preferable.
A: tan δ peak temperature is 20 ° C. or more and less than 35 ° C. B: tan δ peak temperature is 5 ° C. or more and less than 20 ° C., or 35 ° C. or more and less than 50 ° C. C: tan δ peak temperature is less than 5 ° C. or 50 ° C. or more.

[Example 2]
Polyvinyl butyral resin PVB-1 (100 parts by mass) and 3G8 (10 parts by mass) shown in Table 1 were melt-kneaded, and the resulting melt-kneaded product was extruded into a strand shape and pelletized. The obtained pellet was melt-extruded using a single screw extruder and a T die, and a 50 μm thick polyvinyl acetal layer (1) was obtained using a metal elastic roll. A sheet (A) was obtained in the same manner as in Example 1 except that the obtained polyvinyl acetal layer (1) was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 3]
A polyvinyl acetal layer (2) was obtained using 55 parts by mass of di (butoxyethoxyethyl) adipate (hereinafter referred to as “DBEEA”) instead of 40 parts by mass of a mixture of 3G8 and DBEA (mass ratio 10/1). Except for this, a sheet (A) was obtained in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 4]
A sheet (A) was obtained in the same manner as in Example 1 except that the thickness of the polyvinyl acetal layer (1) was 10 μm, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 5]
A sheet (A) was obtained in the same manner as in Example 1 except that the thickness of the polyvinyl acetal layer (1) was 100 μm, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 6]
A compound in which an average of 3 molecules of propylene oxide is added to 3G8 and 1 molecule of bisphenol A instead of 40 parts by mass of a mixture of 3G8 and DBEA (mass ratio 10/1) (hereinafter referred to as “BP-3P”) A sheet (A) was obtained in the same manner as in Example 1 except that 60 parts by mass of the mixture (mass ratio 3/2) was used to obtain the polyvinyl acetal layer (2), and the same evaluation as in Example 1 was performed. It was. The results are shown in Table 2.

[Example 7]
Polyvinyl butyral resin PVB-2 (100 parts by mass) listed in Table 1 and 40 parts by mass of a mixture of 3G8 and DBEA (mass ratio 10/1) were melt-kneaded, and the resulting melt-kneaded product was extruded into a strand shape. And pelletized. The obtained pellets were melt-extruded using a single-screw extruder and a T die, a sheet having a thickness of 400 μm was produced using a metal elastic roll, and the 10-point average surface roughness Rz on one side was 35 μm. A concavo-convex structure was formed on to obtain a polyvinyl acetal layer (1). Moreover, the sheet | seat produced similarly was made into the polyvinyl acetal layer (2). A sheet (A) was obtained in the same manner as in Example 1 except that the obtained polyvinyl acetal layer (1) and polyvinyl acetal layer (2) were used, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 8]
In the production of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2), a sheet (A) was obtained in the same manner as in Example 7 except that the step of forming the concavo-convex structure was not performed. Evaluation was performed. The results are shown in Table 2.

[Example 9]
Polyvinyl butyral resin PVB-2 shown in Table 1 (100 parts by mass) and 30 parts by mass of a mixture of 3G8 and DBEA (mass ratio 10/1) were melt-kneaded, and the resulting melt-kneaded product was extruded into a strand shape. And pelletized. The obtained pellets were melt-extruded using a single-screw extruder and a T die, a sheet having a thickness of 400 μm was produced using a metal elastic roll, and the 10-point average surface roughness Rz on one side was 35 μm. A concavo-convex structure was formed on to obtain a polyvinyl acetal layer (1). Further, the polyvinyl butyral resin PVB-2 (100 parts by mass) shown in Table 1 and 50 parts by mass of DBEEA were melt-kneaded to prepare a sheet having a thickness of 400 μm in the same manner as the polyvinyl acetal layer (1), Further, a concavo-convex structure was formed on one side so that the ten-point average surface roughness Rz was 35 μm, and a polyvinyl acetal layer (2) was obtained. A sheet (A) was obtained in the same manner as in Example 1 except that the obtained polyvinyl acetal layer (1) and polyvinyl acetal layer (2) were used, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 10]
A sheet (A) was obtained in the same manner as in Example 7 except that the thickness of the polyvinyl acetal layer (1) was 200 μm and the thickness of the polyvinyl acetal layer (2) was 800 μm, and the same evaluation as in Example 1 was performed. went. The results are shown in Table 2.

[Example 11]
Sheet (A) in the same manner as in Example 7 except that DBEEA was used in place of the mixture of 3G8 and DBEA (mass ratio 10/1) in preparation of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2). And the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 12]
In the production of the polyvinyl acetal layer (1), instead of 3G8 (10 parts by mass), 20 parts by mass of a mixture of 3G8 and DBEA (mass ratio 10/1) was used, and in the production of the polyvinyl acetal layer (2), 3G8 and DBEA The amount of the mixture used (mass ratio 10/1) was 20 parts by mass, and the sheet (A) was prepared in the same manner as in Example 2 except that the treatment for forming irregularities on the surface of the polyvinyl acetal layer (2) was not performed. And the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Example 13]
In the production of the polyvinyl acetal layer (2), a sheet (A) was obtained in the same manner as in Example 1 except that the polyvinyl butyral resin PVB-3 shown in Table 1 was used instead of PVB-2. The same evaluation was performed. The results are shown in Table 2.

[Example 14]
In the production of the polyvinyl acetal layer (2), a sheet (A) was obtained in the same manner as in Example 1 except that the polyvinyl butyral resin PVB-4 shown in Table 1 was used instead of PVB-2. The same evaluation was performed. The results are shown in Table 2.

[Comparative Examples 1 and 2]
A sheet was obtained in the same manner as in Example 1 except that a sheet prepared in the same manner as the polyvinyl acetal layer (1) was used as the polyvinyl acetal layer (2), and the same evaluation as in Example 1 was performed. The results are shown in Table 2.
As described later, in Comparative Example 1, in order to impart penetration resistance, it was necessary to use an interlayer film for laminated glass (C) when producing laminated glass. On the other hand, in Comparative Example 2, since the interlayer film for laminated glass (C) was not used, the penetration resistance was poor.

[Comparative Example 3]
In the production of the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2), a sheet was obtained in the same manner as in Example 11 except that the amount of DBEEA used was 85 parts by mass, and the same evaluation as in Example 1 was performed. went. The results are shown in Table 2.

[Comparative Example 4]
A sheet was obtained in the same manner as in Example 1 except that the polyvinyl acetal layer (2) was not used, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Comparative Example 5]
A sheet was obtained in the same manner as in Example 1 except that a PET film having a thickness of 50 μm was used instead of the polyvinyl acetal layer (1), and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[Production of laminated glass]
The sheets (A) or sheets obtained in Examples and Comparative Examples were cut into dimensions of 10 cm long × 10 cm wide and placed on a glass having a length of 10 cm, a width of 10 cm, and a thickness of 3 mm. On top of that, a glass having a length of 10 cm, a width of 10 cm, and a thickness of 3 mm was stacked. However, in Comparative Example 1, the laminated glass intermediate film (C) is disposed on the polyvinyl acetal layer (1) side of the sheet, and in Comparative Example 4, the laminated glass intermediate film (C) is disposed on the conductive structure side of the sheet. In Comparative Example 5, a laminated glass interlayer (C) was placed on the PET film side of the sheet, and then placed between the two glasses. Here, as the interlayer film for laminated glass (C), polyvinyl butyral resin PVB-2 (100 parts by mass) shown in Table 1, 3G8 (36.4 parts by mass), DBEEA (3.6 parts by mass) Are melt-kneaded, the obtained melt-kneaded product is extruded into a strand shape, pelletized, melt-extruded using a single-screw extruder and a T-die, and a metal elastic roll is used to form a sheet having a thickness of 800 μm. What was done was used. Subsequently, this was put in a vacuum bag and reduced in pressure for 15 minutes at room temperature using a vacuum pump. Then, the temperature was raised to 100 ° C. while reducing the pressure, and the mixture was heated as it was for 60 minutes. After the temperature was lowered, the pressure was returned to normal pressure, and the laminated glass after prelaminating was taken out. Thereafter, this was put into an autoclave and treated at 140 ° C. and 1.2 MPa for 30 minutes to produce a laminated glass.

The obtained laminated glass was cut into a size of 5 cm × 5 cm, the haze was measured according to JIS R 3106 using a haze meter, and evaluated according to the following criteria. The results are shown in Table 2. A haze value of the laminated glass of 1.0 or less indicates that the transparency of the sheet is high, and a value of 0.6 or less indicates that the transparency of the sheet is very high.
A: Haze value is 0.6 or less B: Haze value is more than 0.6 to 0.8 or less C: Haze value is more than 0.8 to 1.0 or less D: Haze value is more than 1.0

Claims

Polyvinyl acetal layer (1) containing 100 parts by mass of polyvinyl acetal (1) and 0 to 200 parts by mass of plasticizer, and polyvinyl acetal layer (2) containing 100 parts by mass of polyvinyl acetal (2) and 0 to 200 parts by mass of plasticizer And a multilayer structure in which two or more sheets (A) comprising a conductive structure disposed between the polyvinyl acetal layer (1) and the polyvinyl acetal layer (2) are overlapped, the sheet (A ) In which the total content of the plasticizer contained in the sheet (A) is 10 to 80 parts by mass, when the total content of the polyvinyl acetal (1) and the polyvinyl acetal (2) contained in body.
The multilayer according to claim 1, wherein at least one of the content of the plasticizer contained in the polyvinyl acetal layer (1) and the content of the plasticizer contained in the polyvinyl acetal layer (2) is 10 parts by mass or more. Structure.
One of the content of the plasticizer contained in the polyvinyl acetal layer (1) and the content of the plasticizer contained in the polyvinyl acetal layer (2) is 0 to 10 parts by mass, and the other is 10 The multilayer structure according to claim 1, wherein the multilayer structure is not less than 80 parts by mass.
The multilayer structure according to any one of claims 1 to 3, wherein the sheet (A) has an uneven structure on at least one surface thereof.
The multilayer structure according to claim 4, wherein the average surface roughness of at least one surface of the sheet (A) is 15 to 70 µm.
The multilayer structure according to any one of claims 1 to 5, wherein the sheet (A) is wound on a core in a multilayer structure that is overlapped in a roll shape.
The multilayer structure according to any one of claims 1 to 6, wherein the conductive structure is a heat generating conductive structure.
The multilayer structure according to any one of claims 1 to 7, wherein the conductive structure is an etching structure of a metal foil.
The multilayer structure according to claim 8, wherein the metal foil contains copper.
The multilayer structure has an adhesive layer between at least one of the polyvinyl acetal layer (1) and the conductive structure and between the polyvinyl acetal layer (2) and the conductive structure. Item 10. The multilayer structure according to any one of Items 1 to 9.
The multilayer structure does not have an adhesive layer between the polyvinyl acetal layer (1) and the conductive structure and between the polyvinyl acetal layer (2) and the conductive structure. The multilayer structure according to any one of 1 to 9.
The multilayer structure according to any one of claims 1 to 11, wherein the degree of polymerization of at least one of the polyvinyl acetal (1) and the polyvinyl acetal (2) is 800 or more.
The multilayer structure according to any one of claims 1 to 12, wherein the degree of polymerization of the polyvinyl acetal (1) is less than 1500, and the degree of polymerization of the polyvinyl acetal (2) is 1500 or more.
The polyvinyl acetal (1) is represented by the formula (1):

The polyvinyl acetal (2) has the structure represented by formula (2):

Wherein R1 and R2 are each independently a hydrogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and R1 and R2 have the same carbon number. The multilayer structure according to any one of claims 1 to 13.
When the degree of acetalization of the polyvinyl acetal (1) is A 1 mol% and the degree of acetalization of the polyvinyl acetal (2) is A 2 mol%, the absolute value of the difference between A 1 and A 2 is 5 mol%. The multilayer structure according to any one of claims 1 to 14, wherein
The amount of hydroxyl groups of the polyvinyl acetal (1) and H 1 mol%, the hydroxyl group content of the polyvinyl acetal (2) When with H 2 mol%, the absolute value of the difference of an H 1 and H 2 is less than 5 mol% The multilayer structure according to any one of claims 1 to 15, wherein
The plasticizer content in the polyvinyl acetal layer (1) is smaller than the plasticizer content in the polyvinyl acetal layer (2), and the polymerization degree of the polyvinyl acetal (1) is greater than the polymerization degree of the polyvinyl acetal (2). The multilayer structure according to any one of claims 1 to 16, which is small.
The multilayer structure according to any one of claims 1 to 17, wherein the plasticizer contains an ether ester compound.
Two sheets (A) are stacked so that the surface on the polyvinyl acetal layer (1) side and the surface on the polyvinyl acetal layer (2) side are in contact with each other, and 0 ° in a direction perpendicular to the surface at 23 ° C. and 50% RH. The multilayer structure according to any one of claims 1 to 18, wherein a peeling force showing blocking resistance after applying a pressure of 0.02 MPa for 48 hours is 30 N / 30 mm or less.
The polymerization degree of the polyvinyl acetal (1) is smaller than the polymerization degree of the polyvinyl acetal (2), and the thickness of the polyvinyl acetal layer (1) is smaller than the thickness of the polyvinyl acetal layer (2). A multilayer structure according to any one of the above.
When the temperature at which tan δ of the composition constituting the polyvinyl acetal layer (1) takes a maximum value is Tg 1 , and the temperature at which the tan δ of the composition constituting the polyvinyl acetal layer (2) takes a maximum value is Tg 2 The multilayer structure according to any one of claims 1 to 20, wherein at least one of Tg 1 and Tg 2 is 5 ° C or higher.
The multilayer structure according to any one of claims 1 to 21, wherein the sheet (A) has a terminal for receiving electric power or an electric signal arranged so as to protrude outward.