JP2006181981A - Spacer for heating and burning - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spacer for heating and burning of the shape of a surface which is lightweight, excels in handling ease, has no adhesion of dust or the like, and which can inhibit the generation of the blemishes to the surface of a plane-shape laminated member when piling up the plane-shape laminated members through the spacer in multistage and carrying out heating and burning. <P>SOLUTION: The spacer for heating and burning comprises a coating layer at least on one surface of a substrate film, wherein the above substrate film is a polyester based film having the thickness of 120-350 μm and the amount of film subduction of at least 10 μm at time of giving the load of 9.8×10<SP>3</SP>Pa to the above substrate film, furthermore, the above coating layer consists mainly of at least one sort of resin chosen from a polyester based resin, an acrylic based resin and a urethane based resin having the structure of cross-linkage and a polymer based antistatic agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat-firing spacer used between the laminated members in a heat-firing step in which planar laminated members laminated through an adhesive are stacked in multiple stages and then heat-treated to cure the adhesive. More specifically, the present invention relates to a heating and firing spacer that is less likely to be contaminated by the surface of a member due to the adhesion of dust and contamination by volatile matter from the spacer during heat treatment.

  Conventionally, when a plurality of planar laminated members such as laminated glass plates and laminated steel plates are stacked and fired by heating, various spacers such as glass, glass fiber cloth, and steel plates have been used. These spacers have excellent heat resistance and excellent dimensional stability. However, since the spacers have a high density, when the planar laminated members are stacked in multiple stages, the pressure applied to each laminated member differs between the lower laminated member and the upper laminated member. Therefore, there is a problem that the thickness of the laminated member is not uniform between the upper stage and the lower stage, and it has been desired to reduce the weight of the spacer.

  In order to reduce the weight of the spacer, replacement with a plastic film such as a polyester film or a polyimide film, in particular, a biaxially stretched low specific gravity polyester film having an appropriate elasticity has been studied. By using these films, it is possible to reduce the weight as compared with the case of using a conventionally used steel plate. In addition, handling properties can be improved in terms of thinness and stiffness compared to spacers made of silicon rubber or the like.

  However, plastic films are generally insulative, and reattachment of dust to the laminated member becomes a problem due to dust or the like adhering to the film. Therefore, there is a strong demand for imparting antistatic properties.

  Therefore, as a material for improving the weight reduction and antistatic property of the laminated member, a plastic film for hot press cushioning in which the melting point, cushion rate, thermal shrinkage rate, and surface specific resistance of the film are specified (for example, patents) is exemplified. Reference 1).

  However, when the plastic film is used as a planar heating and firing spacer, a volatile component generated during heat treatment contaminates a laminated member (for example, a laminated glass plate) that directly contacts the planar spacer. Problems arise. Further, when the volatile component is a flammable gas, there is a risk in manufacturing, and therefore, generation of the volatile component is required to be suppressed.

  Furthermore, it is described that even if the plastic film has a configuration in which a cushion rate is sufficiently ensured, a thickness of 30 μm or less cannot absorb deformation, and scratches are generated on the surface of the laminated member. Moreover, even if the cushion rate is a film with a low cushion rate of less than 5%, which is outside the scope of the claims of Patent Document 1, if the entire film is thick, the surface of the laminated member will not be damaged. They found out. Therefore, it was found that the cushion rate is not necessarily appropriate as an index for suppressing the occurrence of scratches on the surface of the laminated member.

  In recent years, in such a baking process, the area of the spacer per sheet has increased due to an increase in the processing area. For this reason, it has been more strongly desired to make the spacers stiffer and not too heavy so that the spacers are easy to handle.

From these viewpoints, a film having both lightness and handleability, capable of preventing generation of scratches, having antistatic properties, and further suppressing generation of volatile components is important as a heating and firing spacer.
Japanese Patent Laid-Open No. 5-24060 (pages 1 and 2, Table 1)

  Under the circumstances described above, the problem to be solved by the present invention is that it is lightweight and excellent in handleability, has no adhesion of dust and the like, and is laminated and heated and fired by laminating planar laminated members via spacers. An object of the present invention is to provide a planar heating / firing spacer capable of suppressing the occurrence of scratches on the surface of a planar laminated member.

  In order to solve the above-mentioned problems, the present inventors have intensively studied a spacer for heating and baking having a coating layer on at least one side of a base film, and as a result, the thickness of the base film and the base film The present invention finds that the above-mentioned problems can be solved by adjusting the amount of film sinking when a specific load is applied, and further by using a predetermined resin and a polymer antistatic agent as the main constituent components of the coating layer. Was completed.

That is, the heating and baking spacer of the present invention is a heating and baking spacer having a coating layer on at least one side of the base film, and the base film is a polyester film having a thickness of 120 to 350 μm, And the amount of film sinking when a load of 9.8 × 10 ³ Pa is applied to the base film is 10 μm or more, and the coating layer has a cross-linked structure, a polyester resin, an acrylic resin, and a urethane A spacer for heating and baking, comprising at least one resin selected from a resin and a polymer antistatic agent as main components.

As the base film, a void-containing polyester film having an apparent density of 1.00 to 1.35 g / cm ³ is suitable. The coating layer preferably comprises a polyester resin having a crosslinked structure and a polymer antistatic agent as main components. Further, as the polymer antistatic agent, a resin containing a sulfonate group component in the molecule is suitable.

Since the base film is a polyester film having a thickness of 120 to 350 μm, the spacer for heating and baking of the present invention reduces the occurrence of scratches on the surface of the laminated member while maintaining the handleability during processing. Can do. Moreover, since the film sinking amount when a load of 9.8 × 10 ³ Pa (100 gf / cm ² ) is applied to the base film is 10 μm or more, the laminated members are stacked in multiple stages via the spacers. It is possible to reduce the occurrence of scratches on the surface of the laminated member when heated and fired. Furthermore, at least one resin selected from a polyester resin, an acrylic resin, and a urethane resin, wherein the coating layer that the base film has on at least one side thereof has a crosslinked structure, and a polymer antistatic agent, Therefore, when the laminated members are stacked in multiple stages via the spacer and heated and fired, the surface of the laminated member is prevented from being scratched by dust and volatile components are generated from the spacer. This can be suppressed and contamination of the surface of the laminated member can be reduced.

The spacer for heating and baking according to the present invention is a spacer for heating and baking having a coating layer on at least one side of a base film, wherein the base film is a polyester film having a thickness of 120 to 350 μm, and A polyester resin, an acrylic resin, and a urethane resin in which the film sink amount when a load of 9.8 × 10 ³ Pa is applied to the base film is 10 μm or more, and the coating layer has a crosslinked structure The main constituents are at least one resin selected from the group consisting of a polymer and an antistatic agent.

(Base film)
In the heating and firing spacer of the present invention, the base film is a polyester film having a thickness of 120 to 350 μm, and a load of 9.8 × 10 ³ Pa (100 gf / cm ² ) was applied to the base film. The film sinking amount at that time is 10 μm or more. In the present invention, the film thickness and the film sinking amount are measured by the methods described in the following examples. In addition, the film thickness and the film sinking amount are very thin in the coating layer, and the contribution can be almost ignored, so the measured value for the base film without the coating layer, or the base film having the coating layer, that is, heating and baking Any of the measured values for the spacer for use may be used. Therefore, in the present invention, a base film or a polyester film having a coating layer may be simply referred to as a base film or a polyester film.

The lower limit of the thickness of the base film is preferably 150 μm from the viewpoint of maintaining flatness when the laminated members are stacked in multiple stages. The upper limit of the thickness of the base film is preferably 300 μm from the viewpoint of handleability. Moreover, it is preferable that the minimum of the film sinking amount at the time of applying a load of 9.8 × 10 ³ Pa (100 gf / cm ² ) to the base film is 20 μm.

As such a base film, for example, a void-containing polyester film having an apparent density of 1.00 to 1.35 g / cm ³ is preferable. When the apparent density of the void-containing polyester-based film is less than 1.00 g / cm ³ , the back feeling of the film is lowered, and the handleability is likely to deteriorate. When the apparent density of the void-containing polyester-based film exceeds 1.35 g / cm ³ , the amount of film sinking when the specific load is applied is reduced to less than 10 μm, and the planar laminated member is stacked in multiple stages and heated and fired. When doing so, scratches are likely to occur on the surface of the laminated member, and workability (handling properties) may also be reduced. In the present invention, the apparent density is measured by the method described in the following examples. In addition, the apparent density of the coating layer is very thin and its contribution is almost negligible, so the measured value for the void-containing polyester film without the coating layer, or the void-containing polyester film with the coating layer, that is, for heating and firing. Any of the measured values for the spacer may be used.

  In the case where a void-containing polyester film is used as the base film, the base film is used to increase the amount of sinking of the film when the specific load is applied while maintaining the waist of the base film. It is important that the absolute volume (cavity content × unit area × thickness) of the volume of the cavity per unit area is within a predetermined range. Furthermore, the hardness of the film constituent material, the shape and size of the cavities, the distribution state, and the like influence the sinking amount of the film. However, reducing the apparent density of the base film or increasing the void content to increase the cushion ratio of the film is a necessary condition for controlling the amount of film sinking, but is sufficient is not.

  Polyester resins used as raw materials for the base film include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid or esters thereof (for example, alkyl esters such as methyl ester), ethylene glycol, diethylene glycol, 1, It is a polyester resin obtained by polycondensation with glycols such as 3-propanediol, 1,4-butanediol, and neopentyl glycol. These polyester resins include, for example, a direct polymerization method in which an aromatic dicarboxylic acid and a glycol are directly reacted, and an ester exchange method in which an alkyl ester of an aromatic dicarboxylic acid and a glycol are transesterified and then polycondensed. Alternatively, it can be produced by a method of polycondensing a diglycol ester of an aromatic dicarboxylic acid.

  Specific examples of the polyester-based resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate. These polyesters may be homopolymers or copolymerized third components. Among these polyester resins, ethylene terephthalate unit, trimethylene terephthalate unit, butylene terephthalate unit or ethylene-2,6-naphthalate unit is 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more. Polyester resins containing in proportions are recommended.

  In order to set the film sinking amount when applying the above specific load within a predetermined range, it is necessary to use a void-containing polyester film as the base film, that is, to contain a large number of fine cavities inside the base film. preferable. Examples of the method of incorporating cavities inside the base film include, for example, (1) a method in which a foaming agent is contained in a polyester resin and foamed by heat during extrusion or film formation, or foamed by chemical decomposition. (2) A method in which a gas such as carbon dioxide or a vaporizable substance is added and foamed during or after the extrusion of the polyester resin; and (3) a thermoplastic resin incompatible with the resin is added to the polyester resin. Add, melt-extrusion and then uniaxially or biaxially stretch; (4) Add organic or inorganic fine particles to polyester resin, melt-extrusion, then stretch uniaxially or biaxially Can do.

  Among these cavities forming methods, the method of (3) above, that is, a method of adding a thermoplastic resin incompatible with the resin to a polyester resin, and then stretching it uniaxially or biaxially after melt extrusion. Is preferred. Here, as a thermoplastic resin incompatible with the polyester resin (hereinafter sometimes simply referred to as “incompatible thermoplastic resin”), when melt-mixed with the polyester resin by a general method, It is not particularly limited as long as it can be phase-separated. For example, polyolefin resin typified by polypropylene and polymethylpentene, polystyrene resin, polyacrylic resin, polycarbonate resin, polysulfone resin, and cellulose resin. And polyphenylene ether resins.

  Here, examples of the polypropylene-based resin include modified resins obtained by grafting or block copolymerizing other components in addition to homopolymers such as isotactic polypropylene and syndiotactic polypropylene. As the presence state of the polypropylene resin, the resin may be used alone or mixed with other resins, or a propylene unit introduced into the polymethylpentene resin described later as a copolymerization component. May be used.

  The polymethylpentene-based resin is a polymer having units derived from 4-methylpentene-1, preferably 80 mol% or more, more preferably 90 mol% or more, among the basic structural units. Examples of the component include units derived from ethylene units, propylene units, butene-1 units, 3-methylbutene-1 and the like. The polymethylpentene resin preferably has a melt flow rate of 200 g / 10 min or less, particularly preferably 30 g / 10 min or less. This is because if the melt flow rate exceeds 200 g / 10 min, it is difficult to reduce the weight of the heating and firing spacer.

  Furthermore, a polystyrene resin means a thermoplastic resin containing a polystyrene structure as a basic structural unit. For example, a homopolymer such as atactic polystyrene, syndiotactic polystyrene, isotactic polystyrene, or other components may be grafted. Alternatively, block copolymerized modified resins, such as impact-resistant polystyrene resins and modified polyphenylene ether resins, and thermoplastic resins having compatibility with these polystyrene resins, for example, mixtures with polyphenylene ethers, may be mentioned.

  These incompatible thermoplastic resins may be used alone or in combination of two or more. The addition amount of these incompatible thermoplastic resins is preferably 3 to 20% by mass, more preferably 5 to 18% by mass with respect to the polyester resin constituting the void-containing polyester film as the base film. is there. When the amount of incompatible thermoplastic resin added is less than 3% by mass, there is a limit to increasing the amount of voids generated, and when comparing with the film thickness being constant, the above specific load is applied. The amount of film sinking may decrease. When the amount of the incompatible thermoplastic resin added exceeds 20% by mass, the stretchability of the film may be remarkably impaired, and the heat resistance, strength, and waist strength may be impaired.

  In addition, the void-containing polyester-based film may contain inorganic or organic particles in the polyester-based resin or the incompatible thermoplastic resin, as necessary, in order to improve the concealability and the like. Such inorganic or organic particles may be appropriately selected according to need and are not particularly limited, but silica, kaolinite, talc, calcium carbonate, zeolite, alumina, barium sulfate, carbon black, oxidation Examples include zinc, titanium oxide, zinc sulfide, and organic white pigments. These particles may be used alone or in combination of two or more.

As a film raw material suitable for setting the apparent density of the void-containing polyester film to 1.00 to 1.35 g / cm ² , for example, polyethylene terephthalate resin is 80.0 to 98.0% by mass, and polystyrene resin is 0. 0.5-10.0 mass%, polypropylene resin 0.5-10.0 mass%, polymethylpentene resin 0.5-10.0 mass%, titanium oxide particles 0.5-20.0 mass% The composition which consists of is mentioned.

  Furthermore, in order to improve the handleability of the film, the void-containing polyester film can be formed into a multilayer coextrusion structure. In this case, a feed block may be installed immediately above the die, and one raw material or both surfaces of one polymer layer, or another raw material may be supplied and laminated between two polymer layers, and then supplied to the flat die. A multi-manifold die may be used as a co-extrusion method other than the feed block method.

  In the spacer for heating and firing of the present invention, the base film can contain a white pigment selected from titanium oxide, calcium carbonate, barium sulfate and a composite thereof in a proportion of 1 to 25% by mass. In addition, coloring agents, light fasteners, fluorescent brighteners, antioxidants, heat stabilizers, UV inhibitors, antistatic agents, lubricants, electrostatic adhesion imparting agents (alkaline earth metal compounds and / or alkali metal compounds) And an additive such as a phosphorus compound) can be contained within a range that does not impair the effects of the present invention.

  In addition, the base film may have a single layer structure made of only a polyester film or a multilayer structure having the same or different thermoplastic resin film layers on at least one surface of the polyester film. The base film having such a multilayer structure can be obtained, for example, by a coextrusion method as described above, a coating method, a laminating method in which the layers are bonded through an adhesive layer, or the like. As the thermoplastic resin film layer, a polyester resin (for example, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate) used as a raw material for the polyester film, polyphenylene sulfide, poly Although the film which has 1 type, or 2 or more types, such as an arylate and a polyimide, as a main component can be used, it is not limited to these. The thickness of the thermoplastic resin film layer is such that the base film has the predetermined film thickness, and the amount of film sinking when the specific load is applied to the base film is within the predetermined range. As long as it is not particularly limited.

  Furthermore, the base film is preferably a biaxially oriented polyester film from the viewpoint of mechanical strength and thermal dimensional stability. The method for stretching the polyester film to make it biaxially oriented will be described below with respect to the production of the spacer for heating and baking, taking the void-containing polyester film as an example.

(Coating layer)
The spacer for heating and baking of the present invention has a coating layer on at least one surface of the base film, and the coating layer has at least a crosslinked structure, and is selected from a polyester resin, an acrylic resin, and a urethane resin. One type of resin (hereinafter sometimes referred to as “resin having a cross-linked structure”) and a polymeric antistatic agent are the main constituent components. Here, "main" means that the total amount of the resin having a crosslinked structure and the polymer antistatic agent exceeds 70% by mass with respect to the total mass of the coating layer among the constituent components of the coating layer. Means. This coating layer suppresses the occurrence of scratches on the surface of the laminated member due to adhesion of dust when the planar laminated member is stacked and heated and fired in a multi-stage manner via a spacer, and the volatile component from the spacer. Is suppressed, and has a function of reducing contamination on the surface of the laminated member.

  The total amount of the resin having a crosslinked structure and the polymer antistatic agent in the coating layer is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total mass of the coating layer. . In addition, the ratio of the resin having the crosslinked structure to the polymer-based antistatic agent is preferably 70/30 to 98/2, and more preferably 80/20 to 95/5 in terms of solid mass ratio. is there. Furthermore, the thickness of the coating layer is preferably 0.01 to 2.0 [mu] m, more preferably 0.02 to 1.0 [mu] m, as the resin solid thickness after stretching. In addition, the thickness of a coating layer shall measure the average thickness of a coating layer by observing the cross section of the spacer for heating and baking with an electron microscope.

<Resin having a crosslinked structure>
The resin having a crosslinked structure may be a resin crosslinked with a curing agent or a resin that is self-crosslinked without using a curing agent.

  When a polyester resin is used as the curing agent crosslinking type resin, examples of the curing agent for crosslinking the resin include isocyanate compounds, oxazoline compounds, and epoxy resins.

  When an acrylic resin is used as the curing agent-crosslinking resin, epoxy resins, alkyd resins, amine derivatives (for example, hexamethoxymethyl melamine and / or amine, melamine) are used as the curing agent for crosslinking the resin. , Diamine, urea, cyclic ethyleneurea, cyclic propyleneurea, thiourea, cyclic ethylenethiourea, alkylmelamine, arylmelamine, benzoguanamine, guanamine, alkylvanamine, arylguanamine) and condensation products of aldehydes (eg formaldehyde) Can be mentioned. Of these curing agents, the condensation product of melamine and formaldehyde is preferred. The curing agent for crosslinking the acrylic resin is preferably selected from those capable of undergoing a thermal crosslinking reaction at the stretching and / or heat treatment temperature during film production.

  When a urethane-based resin is used as the curing agent-crosslinking resin, as a curing agent for crosslinking the resin, propylene oxide is added to polyhydric alcohols (for example, trimethylolpropane, glycerin, sorbitol, ethylenediamine, etc.) Polyether polyol) and polyamines (for example, aliphatic polyamines such as ethylenediamine, diethylenetriamine, and triethylenetetramine, aliphatic polyamines modified with phenolic resins, epoxy resins, and the like).

  Self-crosslinking type resin, for example, by introducing units containing functional groups such as carboxyl groups and blocked isocyanate groups into polyester resins, acrylic resins or urethane resins to control the composition ratio of acid groups in the resin Can be obtained. Of these self-crosslinking resins, polyester-based graft copolymers in which an acid anhydride having at least one double bond is grafted to a polyester-based resin are particularly suitable.

  Here, the “polyester-based graft copolymer” means that all polyester-based resin molecules are graft-copolymerized with the acid anhydride as described above, or the polyester-based resin with the acid as described above. It means a mixture of graft copolymer molecules grafted with anhydrides and unreacted polyester resin molecules not grafted with acid anhydrides as described above. The polyester-based graft copolymer can form crosslinks between resin molecules by the action of the unit by introducing a unit derived from the above acid anhydride into the polyester-based resin. For example, when a coating solution containing a polyester-based graft copolymer as a main component is prepared, the acid anhydride group in the resin molecule is changed to a carboxyl group by hydrolysis or the like in the coating solution. Then, the application liquid is applied to the base film, and the heat history given when the coating layer is formed by drying or the like forms an acid anhydride group between resin molecules, or the activity of other molecules A crosslinked structure is formed between resin molecules by, for example, extracting an hydrogen group to form an ester group.

<Polymer antistatic agent>
As the polymer antistatic agent to be contained in the coating layer, for example, a resin containing a sulfonate group component in the molecule (for example, polystyrene sulfonate) is suitable. The number average molecular weight of the resin containing a sulfonate group component in the molecule is preferably 1,000 to 1,000,000, and more preferably 5,000 to 1,000,000.

  A characteristic of a resin containing a sulfonate group component in the molecule is the high hydrophilicity of the sulfonate group component. Examples of resins containing a sulfonate group component in the molecule include homopolymers such as polystyrene sulfonate sodium, potassium, lithium, ammonium, and phosphonium salts; acrylic monomers such as acrylate or methacrylate And copolymers of styrene sulfonic acid monomers; copolymers of various metal / amine salts of acrylamidomethylpropane sulfonic acid and unsaturated monomers; and the like. Here, the sulfonate may be a mixture of a metal salt and an amine salt.

(Manufacture of spacers for heating and firing)
Although the manufacturing method of the heat-firing spacer is not particularly limited, a typical example will be described below in which a void-containing polyester biaxially stretched film is used as the polyester film of the base film.

  First, in a process of melting and extruding a film raw material, a thermoplastic resin incompatible with the resin is dispersed in a polyester resin. As the polyester-based resin and the incompatible thermoplastic resin, for example, those supplied in the form of pellets may be used, but are not limited thereto.

  A raw material that is melted into a film and put into an extruder for extrusion molding may be prepared by mixing these resins with a pellet according to the target composition. However, the polyester resin used as the raw material for the base film and the thermoplastic resin that is incompatible with the resin generally differ greatly in specific gravity, and are re-separated in the process where the pellets once mixed are supplied to the extruder. It is preferable to add a device that does not. As a preferable example of the countermeasure for this, there is a method in which a part or all of the raw resin is combined and kneaded in advance, pelletized, and prepared as a master batch pellet. In the following embodiment, this method is used, but the above-mentioned countermeasure is not limited to this as long as the effect of the present invention is not hindered.

  In addition, in the extrusion of a mixed system of these mutually incompatible resins, the incompatible resin reaggregates due to the function of reducing the interfacial energy of the resin even after being mixed and finely dispersed in the molten state. There is a nature. This is a phenomenon in which an incompatible resin is coarsely dispersed when an unstretched film is extruded to hinder the desired physical properties.

  In order to prevent this, when molding a polyester film, it is preferable to finely disperse an incompatible thermoplastic resin in advance in the polyester resin using a twin screw extruder having a higher mixing effect. If this is difficult, it is also preferable to supply the raw material resin from the extruder to the feed block or the die through a static mixer as an auxiliary means. As the static mixer used here, a static mixer, an orifice, or the like can be used. However, when these methods are employed, care must be taken because the resin that has been thermally deteriorated may remain in the melt line.

  In addition, since it is thought that reaggregation of the incompatible resin in a molten state proceeds with time in a low shear state, reducing the residence time in the melt line from the extruder to the die is a fundamental solution. In this case, the residence time in the melt line is preferably 30 minutes or less, and more preferably 15 minutes or less.

The conditions for the orientation treatment by stretching and heat-treating the unstretched film obtained as described above are closely related to the formation of cavities and the physical properties of the obtained film. Therefore, the stretching and heat treatment conditions are controlled so that the thickness of the base film after stretching and heat treatment is 120 to 350 μm, and the void content inside the film is 10 to 50% by volume. The void-containing polyester film produced under such stretching and heat treatment conditions can have an apparent density of 1.00 to 1.35 g / cm ³ and 9.8 × 10 ³ Pa (100 gf / cm ^2). ), The amount of film sinking can be 10 μm or more.

  Hereinafter, the stretching and heat treatment conditions will be described by taking the most general sequential biaxial stretching method, particularly a method of stretching an unstretched film in the longitudinal direction (longitudinal direction) and then in the width direction (transverse direction).

  In the longitudinal stretching step, stretching is performed between two or many rolls having different peripheral speeds. As a heating means at this time, for example, a method using a heating roll or a non-contact heating method may be used, or they may be used in combination. However, in order to develop a large number of cavities at the interface between the polyester resin and the incompatible thermoplastic resin dispersion inside the film, in the longitudinal direction, for example, 3 to 5 times at a temperature of Tg to (Tg + 50 ° C) Longitudinal stretching is preferred. Next, the longitudinally uniaxially stretched film is introduced into a tenter, and is preferably stretched in the width direction, for example, at a temperature of Tg to (Tm-10 ° C) 2.5 to 5 times. Here, Tm means the melting point of the polyester resin.

  In addition, the obtained biaxially stretched film is subjected to heat treatment as necessary. The heat treatment is preferably performed in a tenter, for example, preferably at a temperature within the range of (Tm-60 ° C.) to Tm. The upper limit of the heat treatment time is preferably 60 seconds. Furthermore, from the viewpoint of dimensional stability of the base film at the time of heating and firing, it is preferable to perform a 3 to 10% relaxation treatment in the width direction in the latter half of the heat treatment.

  The spacer for heating and firing according to the present invention is used between the laminated members in a heating and firing step in which planar laminated members laminated via an adhesive are stacked in multiple stages and then heat-treated to cure the adhesive. And heat treatment at about 150 to 180 ° C. Therefore, it is important for the polyester film used as the base film of the spacer for heating and firing to reduce the thermal shrinkage at 180 ° C., for example, from the viewpoint of dimensional stability. Specifically, it is preferable that the thermal shrinkage rate after standing at 180 ° C. for 5 minutes is 3% or less in both the longitudinal direction and the width direction.

  In order to make the thermal shrinkage rate at 180 ° C. 3% or less, while keeping the balance with other film properties, the maximum temperature during heat treatment of the film is increased, the heat treatment time is lengthened, and the relaxation treatment temperature is 180 ° C. It is preferable that the temperature is higher than the maximum temperature during heat treatment, the relaxation rate is increased, and the relaxation treatment time is lengthened. These conditions are difficult to set uniquely because the appropriate range varies depending on the raw material composition and the residual stress after stretching, and also varies depending on the apparatus. Therefore, it is preferable to conduct preliminary experiments with some of these conditions in advance and grasp the appropriate ranges of the conditions for heat treatment and relaxation treatment.

  Also, in order to control the curl due to the structural difference between the front and back of the film applied in each process, starting from the difference in crystallinity in the film thickness direction due to the cooling difference during extrusion, for example, positively the structure of the film It is preferable to use a method of generating a difference and complementing an inevitable structural difference to bring the curl value close to zero. Specifically, in the stretching process and the heat treatment process such as longitudinal stretching and lateral stretching, the degree of orientation of the film front and back is independently controlled by setting the temperature or heat quantity of the film front and back to different values, By adopting conditions that balance physical properties, film formation with a curl value of substantially zero is realized.

  In addition, as a basic requirement for the stable production of films with low curl across the entire width, it is also important to form cavities with little change in the film thickness direction by adopting stretching conditions with less thickness unevenness. It is.

  More specifically, the longitudinal curl immediately after film formation is controlled by controlling the structural difference between the front and back of the film during longitudinal stretching, and the lateral curl is controlled by controlling the structural difference between the front and back of the film during lateral stretching and heat treatment. It is preferable to suppress the curl by creating an internal strain in the direction and balancing with the internal strain due to the structural difference between the front and back of the film that inevitably occurs.

  The coating layer is prepared by preparing a coating solution containing a resin having a crosslinked structure and a polymer antistatic agent. Or, apply an unstretched film after longitudinal stretching, and after drying or drying, apply orientation treatment by further transverse stretching and heat treatment, or apply an unstretched film after transverse stretching and dry After or after drying, the film may be formed by further stretching and heat treatment for orientation treatment, or by applying to the film surface after orientation treatment and drying. In addition, as a coating method of the coating liquid, a conventionally known coating method such as a gravure coating method, a kiss coating method, a dip method, a spray coating method, a curtain coating method, an air knife coating method, a blade coating method, a reverse roll coating method can be applied. .

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

  First, the film physical property measurement method and spacer evaluation method used in the following examples are shown below.

(1) Film thickness A standard gauge (No. 900030) is attached to a dial gauge (manufactured by Mitoyo Seisakusho) and installed on a dial gauge stand (No. 7001DGS-M). The thickness when a load of 5 gf is applied to the dial gauge holder is defined as the film thickness.

(2) Cushion ratio A standard gauge (No. 900030) is attached to a dial gauge (manufactured by Mitoyo Seisakusho) and installed on a dial gauge stand (No. 7001DGS-M). The cushion ratio can be calculated by the following equation, where d50 and d500 are the film thicknesses when a load of 50 gf and 500 gf is applied to the dial gauge pressing portion.
Cushion rate (%) = ((d50−d500) / d50) × 100

(3) Amount of sinking A standard gauge (No. 900030) is attached to a dial gauge (manufactured by Mitoyo Seisakusho) and installed on a dial gauge stand (No. 7001DGS-M). Assuming that the film thicknesses when a load of 5 gf and 100 gf is applied to the dial gauge pressing portion are d5 and d100, the sinking amount can be calculated by the following equation.
Subduction amount (μm) = (d5−d100)

(4) Apparent density A sample was accurately cut into a square of 5.00 cm × 5.00 cm, the thickness of the sample piece was measured at 50 points to obtain the average thickness t (μm), and the weight w ( g) is measured to 0.1 mg and calculated by the following formula.
Apparent density (g / cm ³ ) = w / (5 × 5 × t) × 10000

(5) Ash adsorption distance After leaving the sample and ash in an atmosphere of 20 ° C. and 65% RH for 24 hours, the surface is charged by reciprocating cotton 10 times in that atmosphere and rubbing. Then, with this friction surface facing down, the distance at which the ash begins to be adsorbed is determined and used as the ash adsorption distance. In addition, the case where an ash adsorption distance is 20 mm or less is set as favorable ((circle)), and the case where it exceeds 20 mm is set as improper (x).

(6) Determination of the amount of volatile components A sample of 5 cm square is set in the chamber, and after replacing the inside of the chamber with nitrogen for 24 hours, it is heated to 180 ° C. and volatilized while being held for 5 minutes. Collects sexual components. The total amount of volatile components is quantified by gas chromatography, the amount of gas generated per unit mass is calculated, and the determination is made according to the following criteria.
○: ≦ 10 ² μg / mg
×:> 10 ² μg / mg

(7) Handling property Samples were cut into 30 cm x 50 cm, and 100 samples were stacked on a desk with a height of 100 cm and allowed to stand. Next, the operation of pinching the diagonal vertices of the sample at two locations to move them one by one to a position 60 cm wide from the resting place was performed 100 times for 10 persons, and the handling property was determined according to the following criteria.
×: When the probability of occurrence is 3% or more and there are irregularities due to bending observed visually, or when 50% or more of the workers feel that the sheet is heavy during work 〇: When the above does not apply

(8) Scratch prevention property The application surfaces of two samples cut into 5 cm squares were opposed to each other, and a biaxially stretched PET film having a thickness of 100 μm was sandwiched between them. This was held at 100 ° C. for 10 minutes under a load of 50 Pa (500 gf / cm ² ). Thereafter, the scratches or imprints on the surface of the biaxially stretched PET film were visually observed at a position 50 cm away under a 20 W fluorescent lamp, and judged according to the following criteria.
○: No scratches or imprints are observed Δ: 1-5 scratches or imprints are observed ×: 6 or more scratches or imprints are observed

(9) Dirt transfer property The coated surfaces of two 5 cm square samples were opposed to each other, and a glass plate having a cleaned surface was sandwiched therebetween. This was kept at 100 ° C. for 10 minutes under a load of 50 Pa (500 gf / cm ² ). Then, the stain | pollution | contamination of the surface of a glass plate was observed and it determined on the following reference | standard.
○: Dirt is not observed Δ: Slightly cloudy is observed ×: Whitening is observed

Example 1
(Preparation of coating solution)
In a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser, 465 parts by mass of terephthalic acid, 456 parts by mass of isophthalic acid, 29 parts by mass of fumaric acid, 465 parts by mass of ethylene glycol and 364 parts by mass of neopentyl glycol The esterification reaction was carried out from 160 ° C. to 220 ° C. over 3 hours. Next, 0.7 parts by mass of tetra-n-butyl titanate was added, and the temperature was raised from 200 ° C. to 220 ° C. over 1 hour to carry out an esterification reaction. Next, the temperature was raised to 255 ° C., and the reaction system was gradually depressurized, and then reacted for 1 hour 30 minutes under a reduced pressure of 0.1 mmHg to obtain a polyester resin (I-1). The obtained polyester-based resin had a number average molecular weight of 35,000 and a color tone that was light yellow and transparent.

  Next, 75 parts by mass of the polyester resin (I-1) obtained above, 56 parts by mass of methyl ethyl ketone and 19 parts by mass of isopropyl alcohol are placed in a reactor equipped with a stirrer, a thermometer, a reflux apparatus and a quantitative dropping apparatus. The mixture was heated and stirred at 65 ° C. to dissolve the resin. After the polyester resin was completely dissolved, 15 parts by mass of maleic anhydride was added to this solution. Next, a solution prepared by dissolving 10 parts by mass of styrene and 1.5 parts by mass of azobisisobutyronitrile in 12 parts by mass of methyl ethyl ketone was dropped into this solution at 0.1 mL / min, and stirring was further continued for 2 hours. After sampling for analysis from the reaction solution, 5 parts by mass of methanol was added. Next, 300 parts by mass of water and 15 parts by mass of triethylamine were added to the reaction solution and stirred for 1 hour. Thereafter, the internal temperature of the reactor was raised to 100 ° C., and methyl ethyl ketone, isopropyl alcohol and excess triethylamine were distilled off to obtain an aqueous dispersion (I-2) of a self-crosslinking graft polyester resin. The resin obtained by drying the aqueous dispersion (I-2) of this polyester resin was light yellow and transparent in color, and had a glass transition temperature of 65 ° C.

  The polyester aqueous dispersion (I-2) obtained above and lithium polystyrene sulfonate (number average molecular weight 10,000, manufactured by NSC Japan, Inc.) were mixed at a solid content mass ratio of 90/10 to obtain a total resin solid concentration. Was adjusted to be 5 mass% and the solvent was water / isopropyl alcohol = 60/40 (mass ratio) to obtain a coating liquid (I-3).

(Preparation of master pellet)
Polyethylene pentene resin having a melt viscosity (η _O ) of 1,300 poise (Mitsui Chemicals, DX820) 60 mass%, polystyrene resin having a melt viscosity (η _S ) of 3,900 poise (manufactured by Nippon Polystyrene Co., Ltd., G797N) 20 20% by mass of 20% by mass of a polypropylene resin (Grand Polymer, J104WC) with a melt viscosity of 2,000 poise was supplied to a bent twin screw extruder whose temperature was adjusted to 285 ° C. and pre-kneaded. . This molten resin was continuously supplied to a vent type single-screw kneader, kneaded and extruded, and the obtained strand was cooled and cut to prepare an incompatible resin master pellet (M1).

  Further, 50% by mass of anatase-type titanium dioxide particles (manufactured by Fuji Titanium, TA-300) having an average particle size of 0.3 μm were mixed with 50% by mass of polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dL / g produced by a known method. The product was supplied to a vent type twin screw extruder and pre-kneaded. This molten resin was continuously supplied to a vent type single-screw kneader, kneaded and extruded. The obtained strand was cooled and cut to prepare a titanium dioxide-containing master pellet (M2).

(Preparation of film material)
81% by mass of the polyethylene terephthalate resin having an intrinsic viscosity of 0.62 dL / g that was vacuum-dried at 140 ° C. for 8 hours, 9% by mass of the master pellet (M1) that was vacuum-dried at 90 ° C. for 4 hours, and the above 10% by mass of master pellet (M2) was mixed with pellets to obtain a film raw material (C1).

(Manufacture of unstretched film)
In the B layer extruder whose temperature was adjusted to 285 ° C., 70 mass% of the same polyethylene terephthalate resin as used for the film raw material (C1) and 30 mass% of the master pellet (M2) were mixed. These were separately fed to the extruder for layer A whose temperature was adjusted to 290 ° C. The molten resin discharged from the B layer extruder is led to the feedbook through the orifice, and the resin discharged from the A layer extruder is passed through the static mixer to the feedbook, and the layer (B1 Layer), a layer (A layer) composed of polyethylene terephthalate resin and master pellet (M2) was laminated in the order of A layer / B layer / A layer.

  This molten resin was coextruded in a sheet form from a T-die on a rotary cooling roll adjusted to 25 ° C., and was adhered and solidified by an electrostatic application method to produce an unstretched film having a thickness of 920 μm. The discharge amount of each extruder was adjusted so that the thickness ratio of each layer was 1: 8: 1. At this time, the molten resin stayed in the melt line for about 12 minutes, and the shear rate received from the T-die was about 150 / second.

(Manufacture of spacers for heating and firing)
The obtained unstretched film is uniformly heated to 65 ° C. using a heating roll, and 3.4 pairs between two pairs of nip rolls (low speed roll: 2 m / min, high speed roll: 6.8 m / min) having different peripheral speeds. Longitudinal stretching was performed twice. At this time, as an auxiliary heating device for the film, an infrared heater (rated output: 20 W / cm) provided with a gold reflective film in the middle part of the nip roll was placed at a position 1 cm from the film surface facing the both surfaces of the film and heated. . On one side of the uniaxially stretched film thus obtained, the coating solution (I-3) was applied by a reverse kiss coating method so that the solid resin thickness after stretching was 0.05 μm. After coating, it is led to a tenter, heated to 150 ° C. while dried, stretched by a factor of 3.7, fixed in width, subjected to heat treatment at 220 ° C. for 5 seconds, and further relaxed by 4% in the width direction at 200 ° C. By doing this, a spacer for heating and firing having a coating layer on one side of a void-containing polyester biaxially stretched film which is a 100 μm thick polyester film was obtained. In addition, the apparent density of the void-containing polyester film as the base film was 1.10 g / cm ³ .

Example 2
In Example 1, the raw material supplied to the extruder for layer B was changed to 95% by mass of polyethylene terephthalate resin and 5% by mass of polystyrene resin, and the discharge amount was adjusted so that the thickness of the stretched film was 250 μm Then, in the same manner as in Example 1 except that an unstretched film was produced, for heating and baking, having a coating layer on one side of a cavity-containing polyester biaxially stretched film that is a polyester film having a thickness of 250 μm. A spacer was obtained. The apparent density of the void-containing polyester film as the base film was 1.35 g / cm ³ .

  In addition, the base film which comprises the spacer for heating and baking manufactured in Example 2 is a cavity-containing polyester film having a cushion rate of 4%, which is an example corresponding to the comparative example of Patent Document 1, but the thickness is Is 250 μm and the film sinking amount is 12 μm, and thus the obtained heat-fired spacer showed excellent characteristics.

Comparative Example 1
A polyethylene terephthalate chip and a master chip to which polyethylene glycol having a number average molecular weight of 4,000 was added during the polymerization of polyethylene terephthalate were vacuum-dried at 180 ° C. for 3 hours, and then 94% by mass of polyethylene terephthalate and 1% by mass of polyethylene glycol. The polymethylpentene was mixed in a chip state so as to be 5 mass%. These mixed chips were supplied to an extruder B heated to 280 ° C. Further, a polyethylene terephthalate chip containing 14% by mass of calcium carbonate having an average particle size of 1.1 μm (electron microscopy) was dried in the same manner as described above, and then supplied to the extruder A.

  The polymers extruded from the extruders A and B are laminated so as to have a three-layer structure of A / B / A, and are cooled and solidified by a rotary cooling drum having a surface temperature of 25 ° C. while being extruded into a sheet form from a T die. A stretched laminated sheet was obtained. The obtained unstretched sheet was led to a roll group heated to 100 ° C., longitudinally stretched 3.4 times in the longitudinal direction, and cooled by a roll group at 25 ° C. Next, the following coating solution (II-3) was applied to one side of the longitudinally uniaxially stretched film by a reverse kiss coating method so that the solid content thickness of the coated layer after stretching was 0.07 μm. Further, the coated film was guided to a tenter and stretched 3.6 times in the width direction at 145 ° C. while drying the coated layer. Next, heat treatment is performed at 230 ° C. in a tenter, uniformly cooled, cooled to room temperature, wound up, and a coating layer is formed on one side of a void-containing polyester biaxially stretched film which is a polyester film having a thickness of 100 μm. A spacer for heating and baking was obtained. The layer structure of the base film in the obtained spacer for heating and firing was 7 μm / 86 μm / 7 μm.

(Manufacture of coating liquid (II-3))
In a stainless steel autoclave equipped with a stirrer, a thermometer and a partial reflux condenser, 485 parts by mass of terephthalic acid, 480 parts by mass of isophthalic acid, 7.4 parts by mass of dimethyl 5-sodium sulfoisophthalate, and 527 parts by mass of ethylene glycol , And 800 parts by mass of a bisphenol A ethylene oxide adduct (manufactured by Sanyo Chemical Co., Ltd., BPE20F), and esterification reaction was performed from 160 ° C. to 220 ° C. over 3 hours. Next, 0.7 parts by mass of tetra-n-butyl titanate was added, and the temperature was raised from 200 ° C. to 220 ° C. over 1 hour to carry out an esterification reaction. Next, the temperature was raised to 255 ° C., and the reaction system was gradually depressurized, and then reacted for 30 minutes under a reduced pressure of 0.5 mmHg. Thereafter, under melting, 205 parts by mass of ethylene glycol bistrimellitate dianhydride (manufactured by Nippon Nippon Chemical Co., Ltd., TMEG) was added, and the mixture was reacted by stirring at 200 ° C. for 5 minutes in a nitrogen atmosphere. -1) was obtained. The obtained polyester-based resin had a number average molecular weight of 15,000 and a color tone that was light yellow and transparent.

  Next, in a reactor equipped with a stirrer, a thermometer, a reflux device and a quantitative dropping device, 75 parts by mass of the polyester resin (II-2) obtained above, 100 parts by mass of methyl ethyl ketone and 20 parts by mass of tetrahydrofuran were added. Heated at 65 ° C. and stirred to dissolve the resin. After the resin was completely dissolved, neutralization was performed by adding ammonia water in which 10 parts by mass of 28% ammonia water and 100 parts by mass of water were mixed in advance. After stirring for 30 minutes at 60 ° C., 200 parts by mass of water was added to carry out water dispersion. Subsequently, the internal temperature of the reactor was raised to 100 ° C., and the remaining solvent and excess ammonia were distilled off by distillation to obtain an aqueous polyester dispersion (II-2) having no crosslinked structure. The resin obtained by drying this polyester aqueous dispersion was light yellow and transparent in color and had a glass transition temperature of 60 ° C.

  The polyester aqueous dispersion (II-2) obtained above and lithium polystyrene sulfonate (molecular weight: 70,000, manufactured by NSC Japan) are mixed at a solid content mass ratio of 90/10, and the total resin solid concentration is 5 mass. %, The solvent was adjusted to be water / isopropyl alcohol = 60/40 (mass ratio) to obtain a coating solution (II-3).

  In addition, the base film which comprises the spacer for heating and baking manufactured in Comparative Example 1 is a void-containing polyester film having a cushion rate of 15%, which is an example corresponding to the example of Patent Document 1, but handling properties are not limited. It was inferior to.

Comparative Example 2
In Example 1, the raw materials supplied to the extruder for B layer were 85% by mass of polyethylene terephthalate resin and 15% by mass of polystyrene resin, and the discharge rate was adjusted so that the thickness of the stretched film was 150 μm. In the same manner as in Example 1, a heat-fired spacer having a coating layer on one side of a void-containing polyester biaxially stretched film which is a polyester film having a thickness of 150 μm was obtained.

  In addition, the base film which comprises the spacer for heating and baking manufactured in Comparative Example 2 is a void-containing polyester film having a cushion rate of 6%, which is an example corresponding to the example of Patent Document 1, but the thickness is Is 150 μm and the sinking amount is 8 μm, the obtained heat-fired spacer has insufficient scratch-preventing properties and inferior properties.

Comparative Example 3
In Example 1, the raw materials supplied to the B layer extruder were 90% by mass of polyethylene terephthalate resin and 10% by mass of polystyrene resin, and the discharge rate was adjusted so that the thickness of the stretched film was 500 μm. In the same manner as in Example 1, a heat-fired spacer having a coating layer on one side of a void-containing polyester biaxially stretched film which is a 500 μm thick polyester film was obtained. Since the base film constituting the heat-firing spacer produced in Comparative Example 3 was as thick as 500 μm, the obtained heat-firing spacer was inferior in handling properties.

Comparative Example 4
In Comparative Example 1, a void-containing polyester biaxial stretching, which is a polyester film having a thickness of 30 μm, was performed in the same manner as in Comparative Example 1, except that the discharge amount was adjusted so that the thickness of the stretched film was 30 μm. A spacer for heating and baking having a coating layer on one side of the film was obtained. The base film constituting the heat-firing spacer manufactured in Comparative Example 4 had a cushion rate of 15%, but was inferior in handling properties and scratch prevention properties because it was as thin as 30 μm.

Comparative Example 5
In Example 1, a spacer for heating and firing was obtained in the same manner as in Example 1 except that the coating layer was not provided. The spacer was made of only a void-containing polyester biaxially stretched film that is a polyester film having a thickness of 100 μm.

  Table 1 below shows the results of testing the heating and baking spacers manufactured in Examples 1 and 2 and Comparative Examples 1 to 5 by the above measurement method and evaluation method.

  The spacer for heating and baking according to the present invention is less likely to be contaminated by dirt on the surface of the member due to adhesion of dust or volatile matter from the spacer during heat treatment, so that planar laminated members laminated via an adhesive are stacked in multiple stages. Then, it is suitable as a planar heat-firing spacer used between the laminated members in a heat-firing step in which the adhesive is cured by heat treatment.

Claims (4)

A spacer for heating and baking, having a coating layer on at least one surface of a base film, wherein the base film is a polyester film having a thickness of 120 to 350 μm, and 9.8 × 10 ^At least one resin selected from a polyester resin, an acrylic resin, and a urethane resin, in which a film sink amount when a load of ³ Pa is applied is 10 μm or more, and the coating layer has a crosslinked structure And a high-temperature antistatic agent as main constituents. The spacer for heating and firing according to claim 1, wherein the base film is a void-containing polyester film having an apparent density of 1.00 to 1.35 g / cm ³ .   The spacer for heating and baking according to claim 1 or 2, wherein the coating layer comprises a polyester resin having a crosslinked structure and a polymer antistatic agent as main components.   The spacer for heating and baking according to any one of claims 1 to 3, wherein the polymer antistatic agent is a resin containing a sulfonate group component in the molecule.