JPH04298589A - Masking film - Google Patents

Abstract

PURPOSE:To obtain a masking film which has a necessary flexibility and retains sufficiently high high-temperature dimensional stability and chemical resistance by providing a pressure-sensitive adhesive layer on one side of a specific flexible film made from a copolymeric polyester. CONSTITUTION:A masking film which comprises a flexible film, which is made from a copolyester film with a DELTATcg of 60 deg.C or less and has a tensile Young's modulus of 0.1-50kg/mm<2> at 25 deg.C, a dimensional change of 10% or less at 160 deg.C and a dimensional change of + or -15% or less when immersed in chemicals, and a pressure-sensitive adhesive layer formed on one side of the film. The copolyester preferably contains a long-chain dicarboxylic acid as the soft segment in view of improving the flexibility, high-temperature dimensional stability and chemical resistance. Particularly, the long-chain aliphatic dicarboxylic acid may preferably be a branched long-chain aliphatic dicarboxylic acid. A dimer acid is preferred above all.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking film using a flexible copolymerized polyester film, and more particularly to a film suitable for use in masking when plating electronic parts, printed circuit boards, etc.

0002

[Prior Art] Conventionally, a film made of polyethylene terephthalate, polyimide, soft vinyl chloride, etc., with an adhesive layer formed on one side, has been used as a masking film when plating electronic parts, printed circuit boards, etc. . This masking film is flexible enough to follow the shape of electronic components and circuit boards, has high chemical resistance to organic solvents used in plating pretreatment, and has excellent resistance to plating and drying after washing with water. High-temperature dimensional stability that can handle the temperature is required.

0003

[Problems to be Solved by the Invention] However, the masking films made of polyethylene terephthalate, polyimide, and soft vinyl chloride films that have been used so far have the following problems.

First, films made of polyethylene terephthalate, polyimide, etc. have a large Young's modulus, so the film is too stiff and lacks flexibility, making it difficult to follow the surface of electronic components and circuit boards, leaving gaps in the area to be masked. This may cause the plating solution to enter.

[0005] In this regard, although masking films made of soft vinyl chloride have sufficient flexibility, they have poor chemical resistance and may cause problems such as deformation or whitening of the film. Furthermore, since soft vinyl chloride contains a plasticizer, the plasticizer that bleeds out over time may cause a chemical reaction with chemicals. Furthermore, due to severe dimensional changes at high temperatures, misalignment may occur in the masking area,
The adhesive force of the adhesive layer may not be able to withstand the above-mentioned dimensional changes, and the adhesive layer may peel off.

The present invention focuses on the problems of conventional masking films, and aims to provide a masking film that has sufficient high-temperature dimensional stability and chemical resistance while having the necessary flexibility. shall be.

[0007]

[Means for Solving the Problems] The masking film of the present invention which meets this objective is made of a copolymerized polyester film having a ΔTcg of 60°C or less, a tensile Young's modulus of 0.1 to 50 kg/mm2 at 25°C, and a 160°C Dimensional change is 10% or less when immersed in chemicals, and ±1 dimensional change when immersed in chemicals.
It consists of a flexible film having a content of 5% or less and an adhesive layer formed on one side of the flexible film.

The copolyester constituting the flexible polyester film of the present invention has a cold crystallization temperature (Tcc)
and the difference between the glass transition temperature (Tg) (Tcc-Tg)
It is necessary that ΔTcg defined by is 60°C or less, preferably 50°C or less. If ΔTcg is too large, the tensile Young's modulus may increase over time,
This causes problems such as deterioration of flexibility.

[0009] Specific examples of the composition of the copolyester include the following. That is, as a soft segment, polyoxyalkylene glycol such as polyethylene glycol and polytetramethylene glycol, or HOOC- such as polyε-caprolactone, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, etc.
[CH2] An aliphatic polyester consisting of an aliphatic dicarboxylic acid of n-COOH and an aliphatic and/or alicyclic diol is preferable, and in particular, as a soft segment, an aliphatic polyester containing a long-chain aliphatic dicarboxylic acid is preferable. This is preferable in order to improve flexibility, high-temperature dimensional stability, and chemical resistance.

[0010] In the present invention, the long-chain aliphatic dicarboxylic acid refers to a dicarboxylic acid having an alkylene group having 8 to 60 carbon atoms, such as sebacic acid, eicoic acid, dodecanedioic acid, and dimer acid. A range of 50 to 50 is preferable because it provides good flexibility.

In particular, in the present invention, among long-chain aliphatic dicarboxylic acids, it is preferable to use a long-chain branched aliphatic dicarboxylic acid having a branched structure, and among these, dimer acid is preferably used because of its flexibility and high-temperature size. This is preferable in terms of good stability and chemical resistance. Here, dimer acid is a mixture of a chain branched structure and a cyclic branched structure obtained by a dimerization reaction of unsaturated aliphatic carboxylic acid methyl ester such as methyl oleate. However, it is hydrogenated and has a bromine number of 0.05 to 10 g/100
g, preferably 0.1 to 5 g/100 g, since it is excellent in flexibility, high temperature dimensional stability, and chemical resistance.

The hard segment of the above-mentioned copolymerized polyester has a melting point of 20
0°C or higher, glass transition temperature 90°C or lower, ΔTcg 8
It is preferable that the temperature is 0°C or lower in order to improve chemical resistance, solvent resistance, etc. Specifically, ethylene terephthalate, butylene terephthalate, cyclohexane dimethylene terephthalate, cyclohexane dimethylene cyclohexane dicarboxylate, butylene-naphthalene Preferably, it is composed of at least one selected from aromatic and/or alicyclic ester units such as dicarboxylate. Among these, those having terephthalic acid residues are particularly preferred because they have good chemical resistance.

[0013] Here, the copolymerized polyester preferably used has an intrinsic viscosity of 0.5 to 2.0 dl/g.
, preferably 0.7 to 1.8 dl/g. By setting the intrinsic viscosity within such a range, both film formability and mechanical properties of the polyester film are improved.

Furthermore, the melting point (T
Practically speaking, m) is preferably in the range of 130 to 250°C, more preferably in the range of 140 to 230°C. Further, the glass transition temperature (Tg) is preferably 10°C or lower, more preferably 0°C or lower.

The copolyester of the present invention contains HO-(CH2)2n-OH(n
: Contains at least two types of diol component residues selected from 1 to 10), 40 to 99 mol% of aromatic dicarboxylic acid residues and 60 mol% of long chain aliphatic dicarboxylic acid residues based on the total acid components. It is preferable to contain up to 1 mol%.

Here, the alcohol component HO(CH2)
2n-OH (n: 1 to 10) refers to ethylene glycol, 1,4 butanediol, 1,6 hexanediol, 1
, 8-octanediol, etc., and preferably n is in the range of 1 to 4 in order to improve the mechanical properties and chemical resistance of the flexible film.

[0017] The copolyester in the present invention includes:
It is preferable to contain at least two of the above alcohol components. Here, in the present invention, each alcohol component is defined as being present when it is contained in an amount of 5 mol% or more.

[0018] If an attempt is made to configure the alcohol component into a one-component system, a problem arises in that the self-adhesiveness becomes too strong. In particular, it is preferable for one of the diol components to be 1,4-butanediol, since this provides good mechanical properties.

Although it is permissible to contain a small amount of branched glycol residues such as propylene glycol and neopentyl glycol, it is generally preferred to keep the content to less than 10 mol%, preferably less than 5 mol%. Similarly, an alcohol component containing an ether group such as diethylene glycol is also allowed to be included as a by-product component. It is usually in the range of about 0.01 to 4 mol%.

The copolyester of the present invention preferably contains 40 to 99 mol% of aromatic dicarboxylic acid residues,
Contains 60-1 mol% of long-chain aliphatic dicarboxylic acid residues. If the content of aromatic dicarboxylic acid residues is less than 40 mol%, the durability will be poor. On the other hand, if the aromatic dicarboxylic acid content exceeds 99 mol%, the film loses flexibility and becomes unsuitable as a masking film.

[0021] Here, the aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6 naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, diphenic acid, etc. Among these, terephthalic acid has the highest durability and flexibility. This is preferable because it gives good results. Further, the long-chain aliphatic dicarboxylic acid is as described above.

The flexible film made of the copolymerized polyester of the present invention has a tensile Young's modulus of 0.1 at 25°C.
It is necessary to be in the range of ~50 kg/mm2,
Preferably, it is in the range of 1 to 30 kg/mm2. If the tensile Young's modulus is too small or too large, problems will arise in the winding property during the production of a flexible film, the suitability for processing into a masking film, the suitability for stretching, etc.

[0023] An antioxidant, an antistatic agent, and an inorganic filler may be added to the flexible polyester film constituting the masking film of the present invention, if necessary. By adding an antioxidant, the chemical resistance (solvent resistance, etc.) of the masking film can be improved, and by adding an antistatic agent, the antistatic performance during processing and use of the masking film can be improved, and by adding an inorganic filler. Accordingly, it is possible to improve the blocking resistance and the absorption and/or reflection of infrared rays.

[0024] As the above-mentioned antioxidant, phenolic antioxidants such as 2,6-di-t-butyl-p-cresol, 4,4'-thiobis-(3-methyl-6-t-butylphenol) 2,2-di(4-hydroxyphenyl)propane, 1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane, octadecyl-3-(3,5-di- t-butyl-4-hydroxyphenyl)propionate, pentaerythritol-tetra-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate, 1,3,5-tris(4-t-
butyl-3-hydroxy-2,6-dimethylbenzyl)
Isocyanurate, tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate; thiodipropionic acid esters such as di-n-dodecyl-thiodipropionate, di-n-octadecyl-thiodipropionate pionates, aliphatic sulfides and disulfides such as di-n-dodecyl sulfide, di-n-octadecyl sulfide, di-n-octadecyl disulfide; aliphatic, aromatic or aliphatic-aromatic phosphites and thiophosphites, such as: tri-n-dodecyl-phosphite, tris(n-nonylphenyl)phosphite, tri-n-dodecyl-trithiophosphite,
Examples include phenyl-di-n-nasyl phosphite and di-n-octadecyl-pentaerythritol diphosphite.

Examples of the antistatic agent include quaternary ammonium salts, amines, imidazolines, amine oxidized ethylene adducts, polyethylene glycols, and sorbitan esters.

[0026] Examples of the inorganic filler include silica, talc, calcium carbonate, etc., and these can be used alone or in combination of two or more. The blending amount is 5.0 per 100 parts by weight of polymer.
Up to 3.0 parts by weight, preferably 3.0 parts by weight or less.

The flexible polyester film of the present invention is
It is preferable that the film be substantially non-oriented in order to have good long-term dimensional stability. Here, "substantially non-oriented" means that the degree of orientation of molecular chains is sufficiently small that the anisotropy of mechanical properties and anisotropy of optical properties can be ignored, for example, in the longitudinal direction. The ratio of breaking strength in the width direction is in the range of 0.6 to 1.4, or the absolute value of the difference in refractive index (Nx, Ny, Nz) in the longitudinal direction, width direction, and thickness direction |Ni-Nj|(i ,j=x,y,z,i≠
j) is less than 0.1, preferably less than 0.05. If it has substantial orientation, it may deform if left for a long period of time, causing practical problems.

[0028] The flexible polyester film of the present invention is
The dimensional change at 160°C must be 10% or less. By providing such high-temperature dimensional stability,
It can handle temperatures such as plating and drying after washing with water. The above dimensional stability can be adjusted by heat treatment during film formation.

Furthermore, the flexible polyester film of the present invention has high chemical resistance, with a dimensional change of ±15% or less when immersed in chemicals. For example, it has high solvent resistance that can withstand preliminary treatments such as degreasing, acid treatment, and flux treatment in the plating process. Chemicals used for plating include organic solvents, acids, and alkalis. Examples of organic solvents include ketones such as acetone and methyl ethyl ketone, halogen solvents such as methylene chloride and chloroform, and ester solvents such as ethyl acetate. Alcohol solvents such as isopropyl alcohol and methanol, and aromatic solvents such as toluene and xylene are available. As an acid,
Examples of the alkali include hydrochloric acid and sulfuric acid, and examples of the alkali include ammonia and an aqueous sodium hydroxide solution.

The masking film of the present invention has the flexible polyester film and the adhesive layer formed on one side thereof as main components, and the masking film may be composed only of these elements, or may be composed of other layers. A masking film may also be formed. As an example of including other layers, for example, an adhesive layer is provided on one side of a flexible polyester film, a sheet base material is laminated on the adhesive layer, and an adhesive layer is further provided on the sheet base material. Examples include laminated configurations. When a sheet base material is used in this manner, the sheet base material includes, for example, a sheet-like fiber base material, and is preferably one that is carbonized without being melted by molten zinc (for example, 440 to 550° C.). Examples of such sheet-like fiber base materials include those using organic fibers and inorganic fibers. Examples of organic fibers include woven or nonwoven fabrics of cellulose fibers such as cotton cloth and rayon, and woven fabrics of aromatic polyamide. Alternatively, nonwoven fabrics, carbon fiber woven fabrics, or nonwoven fabrics may be used. Examples of materials using inorganic fibers include woven or nonwoven fabrics made of glass, asbestos, and the like.

For the adhesive layer in the present invention, a polyacrylic acid adhesive, a natural rubber adhesive, a synthetic rubber adhesive, etc. can be used. It is preferable that the material carbonizes in 4 minutes and the carbide temporarily adheres to the adherend.

When performing masking using the masking film of the present invention, the masking film is adhered to the area to be masked using an adhesive layer. After that,
For example, it is plated with hot dip zinc according to a predetermined procedure. Since the masking film has high chemical resistance, the masking film will not be damaged in any way even when subjected to degreasing, acid treatment, and flux treatment as pre-plating treatment steps, and will not peel off due to temperature changes. As mentioned above, if the adhesive is carbonized and the carbide is temporarily attached, the carbonized layer also exhibits a masking effect. The masking film is removed after plating, but even if the above-mentioned carbides are present, they can be easily removed with a wire brush or the like.

Next, a method for manufacturing a masking film according to the present invention will be explained, but of course the method is not limited thereto.

A. Production of copolymerized polyester Aromatic and/or alicyclic dicarboxylic acids constituting a predetermined hard segment, or dimethyl esters thereof, and a soft segment and a corresponding alcohol component are added, and a copolymerized polyester is produced by a well-known polyester polymerization method. get.

B. Manufacture of flexible polyester film for masking film After drying the copolymerized polyester thus obtained, it is melt-extruded from an extruder, extruded in a sheet or cylindrical shape using a T-shaped nozzle or a circular nozzle, and then cooled onto a cooling roll. Alternatively, it is introduced into a coolant such as water and solidified (the sheet-like or cylindrical material obtained in this way is hereinafter referred to as a cast film).The extrusion temperature is usually from melting point +10 to melting point +
The temperature range is 80℃, and the cooling temperature is 5 to 90℃
The temperature is preferably in the range of 15 to 70°C.

Next, the cast film is heat treated, and the heat treatment temperature ranges from Tcc to the melting point (Tm) of the copolyester, preferably from Tcc to Tm.
The temperature range is -10°C. The treatment time is not particularly limited, but is usually from 1 second to 30 minutes.A particularly preferred method is to perform the heat treatment using a heated roll controlled at a predetermined temperature, in hot water, or in steam, as the treatment will be uniform and effective. This is preferable because it is accurate.

[0037] After the heat treatment, the material is introduced into a drying roll or a drying oven as required, cooled to room temperature with a cooling roll, and subjected to surface treatment, etc., as required, and then wound up.

[0038] Applying an adhesive to one side of the obtained film by a conventional method such as coating to form an adhesive layer,
Obtain the prescribed masking film. When the masking film has a multilayer structure as required, sheet base materials and the like may be laminated, and an adhesive layer may be formed on one side of the laminate.

(Method for Measuring Properties and Evaluating Effects) Next, methods for evaluating the characteristics and effects of the masking film of the present invention and the flexible film constituting it will be explained.

(1) Mechanical properties Tensile Young's modulus at 25°C is according to ASTM-
Measure according to D-882-81 (Method A).

(2) Bromine number According to ASTM-D-1159. Unit is g/100g
It is expressed as

(3) Intrinsic viscosity (IV) Measured at 25°C using o-chlorophenol as a solvent. The unit is dl/g.

(4) Melting point (Tm), glass transition temperature (T
g), cold crystallization temperature (Tcc), ΔTcg, determined using a differential scanning calorimeter DSC2 (manufactured by PerkinElmer). The melt was maintained at 280° C. for 5 minutes under a nitrogen stream, and then cooled using liquid nitrogen. When the sample thus obtained is heated at a heating rate of 10° C./min, the change in specific heat due to the transition from the glass state to the rubber state is read and this temperature is defined as the glass transition temperature (Tg). Also,
The exothermic peak temperature accompanying crystallization is called the cold crystallization temperature (Tcc).
The endothermic peak temperature based on crystal melting was defined as the melting point (Tm). Further, ΔTcg is defined by the following formula. ΔTcg=Tcc-Tg

(5) Dimensional change during heat treatment The film has a width of 1
Cut into pieces of 0 mm and 300 mm long, approximately 200 mm.
Marks were placed at intervals of , and changes in the marking intervals were determined when the sample was treated in a hot air oven at 160° C. for 20 minutes without any weight applied.

(6) Chemical resistance A film was immersed in a chemical for 20 minutes in an atmosphere at 25° C., and its dimensions before and after immersion (wet state) were measured to determine dimensional changes. As chemicals, acetone, isopropyl alcohol, toluene, ethyl acetate, 36% hydrochloric acid, and 10% aqueous sodium hydroxide solution were used.

[0046]

[Example] Example 1 As acid components, dimethyl dimerate (manufactured by Unikema, bromine value 1 g/100 g) 10 mol%, adipic acid 5 mol%
and 85 mol% of terephthalic acid, 50 mol% of ethylene glycol and 50 mol% of 1,4-butanediol as alcohol components, and an intrinsic viscosity (IV) of 0.85.
A copolymerized polyester was polymerized. The obtained polymer was vacuum dried at 120°C by a conventional method, melted at 220°C with a 90mmφ extruder, and extruded into a sheet form from a T-die.
Electrostatic casting was carried out in a state where water was condensed on a cooling roll at 20°C. The obtained film was further heat-treated at 80° C. for 10 seconds to obtain a transparent film with a thickness of 100 μm.

A 0.11 mm thick cotton cloth (product number 12B, number of strands 73 x 64 strands/inch) was used as a sheet base material for producing the masking film. As the adhesive, an acrylic adhesive (manufactured by Dainippon Ink Co., Ltd., trade name: Boncoat PS-300 Emulsion) was mixed with water and adjusted to a solid content of 30%. First, the cotton cloth was dipped in this adhesive emulsion and coated on both sides. Then 1
It was dried at 10° C. for 10 minutes to obtain a cotton cloth-based double-sided pressure-sensitive adhesive sheet with a thickness of 0.2 mm. The above-mentioned 100 μm transparent polyester film was attached to one side of this double-sided pressure-sensitive adhesive sheet to obtain a hot-dip galvanized masking tape. This tape was wrapped around a portion of an iron plate having a thickness of 4 mm, a width of 50 mm, and a length of 400 mm to be masked. When this was plated, it showed a good masking effect. In addition, the properties of the flexible polyester film for the masking film are as shown in Table 1, and it has flexibility (Young's modulus), dimensional change characteristics during heat treatment, and chemical resistance that are extremely suitable for the masking film. Met.

Example 2 Using 15 mol% dimethyl dimerate and 85 mol% terephthalic acid as acid components, and using 37 mol% ethylene glycol and 63 mol% 1,4-butanediol as alcohol components, the intrinsic viscosity (IV) A copolymerized polyester of 0.80 was polymerized. A polyester film was obtained from the obtained polymer in the same manner as in Example 1.

A glass nonwoven fabric was used as a sheet-like fiber base material for producing a masking film, and a synthetic rubber adhesive (Toyo Ink Mfg. Co., Ltd., BPS-4300) was used as an adhesive.
% solution diluted to 20% with triol was used. A glass nonwoven fabric was immersed in this, and then dried at 120°C for 10 minutes to obtain a glass nonwoven fabric double-sided adhesive sheet with a thickness of 0.2 mm. The above polyester film was laminated to one side of this double-sided pressure-sensitive adhesive sheet to obtain a masking film. When plating was performed in the same manner as in Example 1, a good masking effect was shown. In addition, as shown in Table 1, a flexible polyester film for masking film was prepared in Example 1.
It showed good characteristics equivalent to that of

Comparative Example 1 To 100 parts by weight of polyvinyl chloride having an average degree of polymerization of about 1300, 50 parts by weight of dioctyl phthalate (DOP: manufactured by Kyowa Hakko Kogyo Co., Ltd.) and 0.1 part by weight of calcium stearate powder as a stabilizer. parts by weight, 0.2 parts by weight of zinc stearate powder, and 10 parts by weight of epoxidized soybean oil were added, and the mixture was kneaded with rolls having a surface temperature of 160°C, and then a press sheet with a thickness of 100 μm was formed.

When a masking tape was prepared in the same manner as in Example 1 and an attempt was made to perform plating, the masking tape was deformed by the solvent used in the pretreatment process, and good masking could not be achieved. Further, as shown in Table 1, the physical properties of the polyvinyl chloride sheet for masking tape change significantly both during high temperature treatment and when immersed in chemicals, making it unsuitable for masking.

[0052]

[Table 1]

[0053]

Effects of the Invention As detailed above, when using the masking film of the present invention, the masking film can be made from a flexible polyester film that has sufficient flexibility and has excellent dimensional change characteristics and chemical resistance during heat treatment. Can be configured. Furthermore, unlike conventional masking films made of soft vinyl chloride, the polyester film constituting the masking film of the present invention does not contain a plasticizer, so there is no problem associated with bleed-out.

Claims (3)

[Claims] Claim 1: Consisting of a copolyester film with ΔTcg of 60°C or less, tensile Young's modulus at 25°C of 0.1 to 50 kg/mm2, dimensional change at 160°C of 10% or less, and dimensional change when immersed in chemicals. 1. A masking film comprising: a flexible film having a pressure of ±15% or less; and an adhesive layer formed on one side of the flexible film. Claim 2: The copolymerized polyester contains HO-(CH2)2n-OH (n: 1 to 10
) contains at least two types of diol component residues selected from
~99 mol%, 60-1 long chain aliphatic dicarboxylic acid residues
2. The masking film according to claim 1, wherein the masking film contains mol %. 3. The masking film according to claim 2, wherein the long-chain aliphatic dicarboxylic acid is a dimer acid.