WO2013038968A1

WO2013038968A1 - Method for producing composite film, and composite film

Info

Publication number: WO2013038968A1
Application number: PCT/JP2012/072579
Authority: WO
Inventors: 栄一井本; 雄太島▲崎▼; 達也北原; 国夫長崎
Original assignee: 日東電工株式会社
Priority date: 2011-09-14
Filing date: 2012-09-05
Publication date: 2013-03-21

Abstract

The purpose is to provide a method for producing a composite film having improved stretching ease, and having a small amount of change in breaking strength when stretched. This method for producing a composite film involves: a step for preparing a standard mixture containing the urethane polymer and one or more types of acrylic monomers; a step for preparing an additive-containing mixture by adding a chain transfer agent in the amount of 0.01-5 parts by weight, inclusive, to 100 parts by weight of the standard mixture; and a step for forming the composite film by hardening this additive-containing mixture. Therein, the tensile strength of break (S2) of a composite film (P2) obtained by hardening the additive-containing mixture is 85-115%, inclusive, of the tensile strength of break (S1) of a composite film (P1) obtained by hardening the standard mixture, and the stress (M2) when the composite film (P2) is stretched by 20% is 90% or less of the stress (M1) when the composite film (P1) is stretched by 20%, or the stretch percentage at break (E2) when the composite film (P2) is stretched and broken is 120% or more of the stretch percentage at break (E1) when the composite film (P1) is stretched and broken.

Description

Method for producing composite film and composite film

The present invention relates to a method for producing a composite film containing a urethane polymer and an acrylic polymer, and a composite film.

A composite film of an acrylic polymer and a urethane polymer is, for example, Japanese Patent Application Laid-Open No. 2003-96140, Japanese Patent Application Laid-Open No. 2003-171411, Japanese Patent Application Laid-Open No. 2004-10661, and Japanese Patent Application Laid-Open No. 2004-10661. It is disclosed in Japanese Patent Application Publication No. 2004-1062. This composite film has tough physical properties such as high strength and high elongation as a film.

The mechanical properties of such a composite film can be controlled by adjusting the type and copolymer composition of the acrylic polymer, the composition of the urethane polymer, the ratio of the acrylic polymer to the urethane polymer, and the like. For example, in order to produce a composite film having a low elastic modulus, measures such as using an acrylic polymer having a low glass transition temperature (Tg) or a high molecular weight urethane polymer can be employed.

JP 2003-96140 A JP 2003-171411 A JP 2004-10661 A Japanese Patent Application Laid-Open No. 2004-10661

However, if the method of changing the composition of the acrylic polymer or urethane polymer as described above is adopted to change the target mechanical properties of the composite film, other mechanical properties other than the target mechanical properties are adopted. As a result, there may be a case where the desired mechanical properties of the composite film as a whole cannot be obtained. In particular, in order to improve workability and increase the functionality, while maintaining the stretch breaking strength of the composite film, such as a decrease in stress when stretching the composite film and an increase in elongation when the composite film is stretched and broken Although improvement of easy stretchability is desired, it is difficult with the conventional method.

The present invention has been made to solve the above-mentioned problems, and the present invention reduces the stress generated when the composite film is stretched by 20% without significantly changing the breaking strength when the composite film is stretched. Another object of the present invention is to provide a method for producing a composite film capable of improving easily stretchability such as an increase in elongation when it is stretched and broken, and a composite film obtained by this production method.

That is, the present invention is a method for producing a composite film containing a urethane polymer and an acrylic polymer,
A reference mixture preparation step for preparing a reference mixture comprising the urethane polymer and at least one acrylic monomer;
An additive mixture preparation step of adding 0.01 parts by weight or more and 5 parts by weight or less of a chain transfer agent to 100 parts by weight of the reference mixture;
A composite film forming step of curing the additive mixture to form a composite film,
The elongation breaking strength S2 of the composite film P2 obtained by curing the additive mixture is a value of 85% to 115% of the elongation breaking strength S1 of the composite film P1 obtained by curing the reference mixture, and the composite film The stress M2 when the P2 is stretched by 20% is 90% or less of the stress M1 when the composite film P1 is stretched by 20%, or when the composite film P2 is stretched and broken. The elongation at break E2 is 120% or more of the elongation at break E1 when the composite film P1 is stretched and broken.

In the production method, when producing a composite film containing a urethane polymer and an acrylic polymer, 0.01 parts by weight of a chain transfer agent is used with respect to 100 parts by weight of a reference mixture containing the urethane polymer and at least one acrylic monomer. Since 5 parts by weight or less is added, the breaking strength when the resulting composite film is stretched and broken (that is, the elongation breaking strength) is 85% of the elongation breaking strength of the composite film before the addition of the chain transfer agent. While maintaining the above value of 115% or less, the stress acting on the composite film when the composite film is stretched by 20% (hereinafter sometimes referred to as “stress at 20% stretch”) M2 is 90% before addition. It can be reduced to the following values, or the elongation rate of the composite film (ie, the elongation at break) E2 when the composite film is stretched and broken is added. Can be increased to 120% or more of the value before, it is possible to improve the easy extensibility of the composite film. In the conventional method, it is difficult to control both of them because of the positive correlation between the breaking strength at elongation and the stress at 20% elongation or the elongation at break, that is, when one is increased, the other is increased. For example, when the stress at 20% elongation is lowered, the breaking strength at elongation is also lowered and the required breaking strength at elongation cannot be achieved, and conversely, when the elongation at break is increased, the breaking strength at elongation is also increased. It will become. It should be noted that the improvement in breaking strength at the time of expansion is not always required, and in some cases, excessive performance (so-called over spec) is obtained, or when easy breakability is required, it acts in the direction of inhibiting breakage. . On the other hand, in the production method, by adding a chain transfer agent, it is possible to easily achieve both maintenance of the elongation fracture strength, which has been difficult in the past, and decrease the stress at 20% elongation or increase the elongation at break. Can do. Although this mechanism is not clear, the composition or structure of the urethane polymer that contributes to the tensile strength at break of the composite film by the addition of a chain transfer agent has little effect on the stress at 20% elongation or the elongation at break. It is presumed that the degree of polymerization of the acrylic polymer was lowered and moderate stress relaxation occurred in the entire composite film. However, the mechanism is not limited as long as the effects of the present invention can be obtained.

In the production method, the urethane polymer preferably contains an acryloyl group-terminated urethane polymer. As a result, the urethane polymer can be provided with copolymerizability with an acrylic monomer, the cohesive force of the whole polymer is improved, the elongation breaking strength is maintained, the stress at 20% elongation is reduced or the elongation at break is increased. It is possible to more easily achieve the increase.

In the production method, in the reference mixture preparation step, the urethane polymer is preferably formed by a reaction between a polyol and an isocyanate in the presence of at least one acrylic monomer. By taking such a step, the range of types of monomers used as a raw material can be widened, and the additive mixture can be easily formed into a film. In this case, in the composite film forming step, the radiation-curable additive mixture is applied onto a substrate to form a coating film, and the coating film is irradiated with radiation to be cured to form a composite film. preferable.

The present invention includes a composite film obtained by the method for producing the composite film.

According to the present invention, the elongation break strength of the composite film is maintained without changing the composition of each of the urethane polymer and the acrylic polymer, the composition ratio of the both, and the like, and the decrease in stress at 20% elongation and the elongation at break It is possible to easily produce a composite film having improved easy stretchability, such as an increase in.

The present invention relates to a method for producing a composite film containing a urethane polymer and an acrylic polymer, a reference mixture preparation step for preparing a reference mixture containing the urethane polymer and at least one acrylic monomer, and 100 wt% of the reference mixture. An addition mixture preparation step of adding 0.01 parts by weight or more and 5 parts by weight or less of a chain transfer agent, and a composite film formation step of curing the addition mixture to form a composite film. In addition, the elongation breaking strength S2 of the composite film P2 obtained by curing the additive mixture is a value of 85% to 115% of the elongation breaking strength S1 of the composite film P1 obtained by curing the reference mixture, and the above The stress M2 when the composite film P2 is stretched by 20% is that the composite film P1 is stretched by 20%. Is a value of 90% or less of the stress M1 at the time of breaking, or the elongation at break E2 when the composite film P2 is stretched and broken is the breakage when the composite film P1 is stretched and broken It is a value of 120% or more of the time expansion rate E1.

Hereinafter, an embodiment of the present invention will be described. In this embodiment, an acrylic monomer alone or in a mixture of two or more, a polyol and a diisocyanate are reacted to form a urethane polymer, and a mixture containing the urethane polymer and the acrylic monomer is subjected to, for example, a peeling treatment. It is applied onto a polyethylene terephthalate film and cured by irradiation with radiation to produce a composite film. In addition, instead of the polyethylene terephthalate film subjected to the release treatment, an appropriate base material can be used, or an adhesive layer is provided on the release substrate such as the polyethylene terephthalate film subjected to the release treatment. A composite film may be formed thereon. Moreover, after forming a composite film, the adhesive layer produced separately may be laminated | stacked and the laminated sheet of an adhesive layer / composite film may be produced.

[Standard mixture preparation process]
In the reference mixture preparation step, a reference mixture including a urethane polymer and at least one acrylic monomer is prepared.

(Urethane polymer)
The urethane polymer is obtained by reacting a polyol and diisocyanate. A catalyst may be used for the reaction between the hydroxyl group of the polyol and the isocyanate. For example, a catalyst generally used in urethane reaction such as dibutyltin dilaurate, tin octoate, 1,4-diazabicyclo (2,2,2) octane can be used.

Polyols are polyether polyols obtained by addition polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc., or dihydric alcohols (for example, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, hexamethylene glycol, etc.) and adipic acid. And polyester polyols composed of a polycondensation product with a divalent basic acid such as azelaic acid and cepatic acid, acrylic polyols, carbonate polyols, epoxy polyols and caprolactone polyols. Among these, for example, polyether polyols such as polyoxytetramethylene glycol (PTMG) and polyoxypropylene glycol (PPG), non-crystalline polyester polyols, non-crystalline polycarbonate polyols and the like are preferably used. These polyols can be used alone or in combination.

The number average molecular weight of the polyol component is not particularly limited, and may be set in consideration of the characteristics of the intended composite film. Among these, from the viewpoint of stably preparing the reference mixture, for example, 400 to 2000 is preferable, and 600 to 1000 is more preferable. In addition, the measuring method of a number average molecular weight can be measured with the following method. A sample is dissolved in THF at 0.1 wt%, and the number average molecular weight is measured by polystyrene conversion using GPC (gel permeation chromatography). Detailed measurement conditions are as follows.
GPC device: Tosoh HLC-8120GPC
Column: manufactured by Tosoh Corporation, (GMHHR-H) + (GMHHR-H) + (G2000HHR)
Flow rate: 0.8ml / min
Concentration: 0.1 wt%
Injection volume: 100 μl
Column temperature: 40 ° C
Eluent: THF

Examples of the diisocyanate include aromatic, aliphatic, and alicyclic diisocyanates. Aromatic, aliphatic, and alicyclic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate. 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4 -Diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methyl Cyclohexane diisocyanate, m- tetramethylxylylene diisocyanate. These diisocyanates can be used alone or in combination. From the viewpoint of urethane reactivity, compatibility with acrylic, and the like, the type and combination of polyisocyanates can be appropriately selected.

In the present embodiment, the usage amount of the polyol component and the diisocyanate component for forming the urethane polymer is not particularly limited. For example, the usage amount of the polyol component is NCO / OH (equivalent ratio) with respect to the diisocyanate component. ) Is preferably 1.0 or more, and more preferably 2.0 or less. When NCO / OH is less than 1.0, the terminal functional group of the urethane molecular chain becomes a hydroxyl group, and the strength of the film tends to decrease. Moreover, if NCO / OH is 2.0 or less, elongation and flexibility can be ensured.

A hydroxyl group-containing acrylic monomer may be added to the urethane polymer. By adding a hydroxyl group-containing acrylic polymer, an acryloyl group can be introduced into the molecule (particularly the terminal) of the urethane polymer, and copolymerization with an acrylic monomer can be imparted. As a result, the cohesive force of the whole polymer can be improved, and both the maintenance of the elongation break strength and the reduction of the stress at 20% elongation or the increase of the elongation at break can be more easily achieved. As the hydroxyl group-containing acrylic monomer, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxyhexyl (meth) acrylate, or the like is used. The amount of the hydroxyl group-containing acrylic monomer used is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the urethane polymer.

(Acrylic monomer)
Examples of acrylic monomers contained in the reference mixture include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, t -Butyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, dodecyl (meth) acrylate, n-octadecyl (meth) acrylate, acrylic Carboxyl group-containing monomers such as acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, and crotonic acid; (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 2-hydroxypropyl phosphate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, (meth) Hydroxyl group-containing monomers such as 12-hydroxylauryl acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate; Monomers having an alicyclic structure such as cyclohexyl (meth) acrylate and isobornyl acrylate; maleic anhydride, And acid anhydride monomers such as itaconic anhydride; sulfonic acid group-containing monomers such as 2-acrylamido-2-methylpropanesulfonic acid and sulfopropyl acrylate; and phosphoric acid-containing monomers such as 2-hydroxyethylacryloyl phosphate. In addition, amide monomers such as N-substituted (meth) acrylamide such as (meth) acrylamide and N-methylolacrylamide, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, Succinimide monomers such as N- (meth) acryloyl-8-oxyoctamethylenesuccinimide, vinyl monomers such as vinyl acetate, N-vinylpyrrolidone, N-vinylcarboxylic acid amides, N-vinylcaprolactam; acrylonitrile, methacrylonitrile Cyanoacrylate monomers such as glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate Acrylic ester monomers such as fluorine, (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; one or more monomers such as methyl (meth) acrylate and octadecyl (meth) acrylate are used be able to. These acrylic monomers are appropriately determined in terms of type, combination, amount of use and the like in consideration of compatibility with urethane, polymerizability upon photocuring such as radiation, and characteristics of the high molecular weight obtained. As is clear from the above examples, the acrylic monomer includes not only a monomer having a structure derived from acrylic acid but also a monomer having a structure derived from methacrylic acid.

Also, other polyfunctional monomers can be added within a range that does not impair the characteristics. Polyfunctional monomers include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol. Examples include tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane acrylate, epoxy acrylate, and polyester acrylate.

The content of the polyfunctional monomer is preferably 1 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the acrylic monomer. If the content of the polyfunctional monomer is 1 part by weight or more, sufficient cohesive force can be obtained in the resulting composite film, and the tensile strength at break can be secured. If the content is 5 parts by weight or less, the elastic modulus is high. Without being too much, the stress at 20% elongation can be reduced or the elongation at break can be increased.

(Preparation of reference mixture)
The reference mixture may be prepared by reacting a polyol and diisocyanate to separately form a urethane polymer, and mixing the urethane polymer and an acrylic monomer at a predetermined ratio. At least one acrylic monomer may be mixed. In the presence, the urethane polymer may be formed by a reaction between a polyol and an isocyanate. Since the range of types of monomers used as a raw material can be widened and the additive mixture can be easily formed into a film, the urethane polymer can be reacted with a polyol and an isocyanate in the presence of at least one acrylic monomer. Is preferably formed.

Specifically, after dissolving the polyol in the acrylic monomer, the diisocyanate and the like are added and reacted with the polyol to adjust the viscosity. After coating this on the base material, etc., using a low-pressure mercury lamp or the like By curing, a procedure of obtaining a composite film can be employed. In this method, the acrylic monomer may be added all at once during the synthesis of the urethane polymer, or may be added in several divided portions. Alternatively, the polyol may be reacted after the diisocyanate is dissolved in the acrylic monomer. According to this method, the molecular weight is not limited and a high molecular weight polyurethane can be produced, so that the molecular weight of the finally obtained urethane can be designed to an arbitrary size.

In any case, the urethane polymer can be formed by mixing the polyol and the diisocyanate and, if necessary, a catalyst and reacting at 60 to 90 ° C. for 2 to 24 hours. Furthermore, a predetermined amount of a hydroxyl group-containing acrylic monomer may be added and reacted at 60 to 90 ° C. for 1 to 12 hours in order to impart copolymerizability with an acrylic polymer. Thereby, a reference mixture can be prepared.

As a compounding ratio of the urethane polymer and the acrylic monomer, the acrylic monomer with respect to a total of 100 parts by weight of the components constituting the urethane polymer (polyol, diisocyanate, and other optional components (such as a hydroxyl group-containing acrylic monomer)). Is preferably added in an amount of 70 to 130 parts by weight, more preferably 80 to 120 parts by weight.

The standard mixture contains, as necessary, commonly used additives such as ultraviolet absorbers, anti-aging agents, fillers, pigments, colorants, flame retardants, antistatic agents and the like that do not impair the effects of the present invention. Can be added within. These additives are used in normal amounts depending on the type. These additives may be added in advance before the polymerization reaction between the polyol and the diisocyanate, or may be added after the formation of the urethane polymer and before the polymerization of the acrylic monomer.

In addition, a small amount of solvent may be added to the reference mixture in order to adjust the viscosity when the additive mixture described below is applied. The solvent can be appropriately selected from commonly used solvents, and examples thereof include ethyl acetate, toluene, chloroform, dimethylformamide and the like. In addition, a solvent may be added at a reference | standard mixture preparation process, and may be added at an addition mixture preparation process.

[Additive mixture preparation process]
In the additive mixture preparation step, 0.01 to 5 parts by weight of the chain transfer agent is added to 100 parts by weight of the reference mixture to prepare an additive mixture.

(Chain transfer agent)
Examples of chain transfer agents include linear or branched alkyl mercaptans such as n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan or t-dodecyl mercaptan, mercaptoacetic acid (thioglycolic acid), tri Sulfur compounds containing mercapto groups such as methylolpropane tris (3-mercaptopropionate) and pentaerythritol tetrakis (3-mercaptopropionate), halogenated hydrocarbons such as carbon tetrabromide, ethanol, isopropanol, ethyl acetate And the like. These chain transfer agents can be used alone or in combination.

The amount of the chain transfer agent used is 0.01 parts by weight or more and 5 parts by weight or less, and 0.01 parts by weight or more and 1 part by weight with respect to 100 parts by weight of a urethane polymer and an acrylic monomer alone or a mixture of two or more. Part or less. If the amount of chain transfer agent used is less than 0.01 parts by weight, the stress generated when the composite film is stretched by 20% is less likely to decrease, or the elongation when the composite film is stretched and broken is difficult to increase. Or On the other hand, when the amount of chain transfer agent used is 5 parts by weight or more, there is a problem that the gel fraction of the composite film is excessively lowered and the solvent resistance and the like are lowered as a film.

(Photopolymerization initiator)
When imparting radiation curability to the additive mixture, a photopolymerization initiator may be added. When a photopolymerization initiator is added to impart radiation curability to the additive mixture, a composite film can be formed only by undergoing radiation curing of the coating film of the additive mixture, and productivity can be improved. Examples of the photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and 2,2-dimethoxy-1,2-diphenylethane-1-one; substituted benzoin ethers such as anisole methyl ether; Substituted acetophenones such as diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxy-cyclohexyl-phenyl ketone; substituted alpha-ketols such as 2-methyl-2-hydroxypropiophenone; 2-naphthalenesulfonyl chloride, etc. Aromatic sulfonyl chlorides; photoactive oximes such as 1-phenyl-1,2-propanedione-2- (O-ethoxycarbonyl) -oxime; 2,4,6-trimethylbenzoyl-diphenyl-thiol Scan fins oxide, bis (2,4,6-trimethylbenzoyl) - such as acylphosphine oxide, such as triphenylphosphine oxide. In this embodiment, the photopolymerization initiator is added in the additive mixture preparation step, but the photopolymerization initiator is not limited to this and may be added in the reference mixture preparation step.

The addition amount of the photopolymerization initiator is not particularly limited, but is selected from the range of 0.01 to 3 parts by weight (preferably 0.1 to 1 part by weight) with respect to 100 parts by weight of the reference mixture (excluding the solvent). can do.

(Preparation of additive mixture)
An addition mixture can be prepared by adding a chain transfer agent and, if necessary, a photopolymerization initiator to the above reference mixture, and mixing at room temperature (about 25 ° C.) or under heating (eg, 40 to 70 ° C.). it can.

[Composite film forming process]
In the composite film forming step, the additive mixture is cured to form a composite film. Although the process of forming the composite film is not particularly limited, in the present embodiment, the additive mixture that has been made radiation curable is applied onto the substrate to form a coating film, and the coating film is irradiated with radiation to be cured. It is preferable to form a film.

Examples of the base material used in the present embodiment (exfoliated if necessary) include polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polyethylene (PE), and polypropylene (PP). , Polyolefin resin such as high density polyethylene, biaxially oriented polypropylene, polyimide (PI), polyether ether ketone (PEEK), polyvinyl chloride (PVC), polyvinylidene chloride resin, polyamide resin, polyurethane resin, polystyrene Thermosetting resins and the like are used in addition to thermoplastic resins such as resin, acrylic resin, fluorine resin, cellulose resin, and polycarbonate resin. Among these, PET is preferably used because it has an appropriate hardness when used for processing precision parts, and is advantageous in terms of variety and cost. The material of the film is preferably determined as appropriate depending on the application and the type of pressure-sensitive adhesive layer provided as necessary. For example, when a UV-curable pressure-sensitive adhesive is provided, a substrate having a high UV transmittance is used. preferable.

Formation of the coating film of the additive mixture can be performed by a conventionally known method, and examples thereof include roll coating, screen coating, and gravure coating. What is necessary is just to determine the thickness of a coating film in consideration of the thickness of the target composite film.

In the present embodiment, the additive mixture is applied onto a release-treated substrate to form a coating film, and α-rays, β-rays, γ-rays, neutron rays, electron beams, etc., depending on the type of photopolymerization initiator. By irradiating with ionizing radiation, radiation such as ultraviolet rays, visible light or the like, the coating film can be cured to form a composite film.

At this time, in order to avoid polymerization inhibition of the acrylic monomer due to oxygen, the release-treated sheet may be placed on the coating film formed on the substrate to block oxygen, or filled with an inert gas. A release liner may be placed in the container to reduce the oxygen concentration.

In this embodiment, the type of radiation and the like and the type of lamp used for irradiation can be selected as appropriate, such as low-pressure lamps such as fluorescent chemical lamps, black lights, and sterilization lamps, metal halide lamps, high-pressure mercury lamps, and the like. A high pressure lamp or the like can be used.

Irradiation amounts such as ultraviolet rays can be arbitrarily set according to required film characteristics. Generally, the dose of ultraviolet rays, 50 ~ 5000mJ / cm ^2, preferably 100 ~ 4000mJ / cm ^2, more preferably 100 ~ 3000mJ / cm ^2. When the dose of ultraviolet ray is less than 50 mJ / cm ^2, may not sufficient polymerization rate can be obtained, when it is more than 5000 mJ / cm ^2, which may cause deterioration.

In addition, the temperature at the time of ultraviolet irradiation is not particularly limited and can be arbitrarily set. However, if the temperature is too high, a termination reaction due to the heat of polymerization is likely to occur, which tends to cause deterioration of characteristics. Is 70 ° C. or lower, preferably 50 ° C. or lower, more preferably 30 ° C. or lower.

By the above procedure, the acrylic monomer is polymerized to become an acrylic polymer, and a composite film cured as a whole can be obtained. When a solvent is added to the additive mixture, a drying step may be provided after radiation curing. The drying temperature may be set according to the type of solvent, and is, for example, about 80 to 160 ° C. Further, when the urethane polymer has an acryloyl group at the terminal, crosslinking between the urethane polymer and the acrylic polymer occurs, and this can be used to control the mechanical properties or chemical properties of the composite film.

When a composite film is formed by curing the reference mixture, a photopolymerization initiator is added to the reference mixture without adding a chain transfer agent, and this mixture is irradiated with radiation in the same procedure as described above to cause a curing reaction. Just do it.

(Composite film)
The following relationship holds regarding the physical properties of the composite film. That is, the elongation breaking strength S2 of the composite film P2 obtained by curing the additive mixture is a value of 85% to 115% of the elongation breaking strength S1 of the composite film P1 obtained by curing the reference mixture, preferably The value is 90% or more and 110% or less. At the same time, the stress M2 when the composite film P2 is stretched by 20% is 90% or less, preferably 80% or less of the stress M1 when the composite film P1 is stretched by 20%. . Since the composite film according to the present embodiment satisfies such a relationship, it is possible to achieve both maintenance of the tensile strength at break and reduction of the stress at 20% elongation, both of which are difficult with the conventional method. The lower limit of the 20% elongation stress M2 is preferably as low as possible. However, if it is too low, the elongation breaking strength S2 may be less than 85% of the elongation breaking strength S1, and therefore it is preferably 10% or more. Alternatively, the elongation at break E2 when the composite film P2 is stretched and broken at the same time as satisfying the stretch breaking strength is equal to the elongation at break E1 when the composite film P1 is stretched and broken. The value is 120% or more, preferably 140% or more. Since the composite film of the present embodiment satisfies such a relationship, it is possible to achieve both maintenance of the elongation at break strength and increase in the elongation at break, which were difficult with the conventional method. The upper limit of the elongation at break E2 is preferably as high as possible, but is preferably 1000% or less from the balance between required characteristics and productivity.

The thickness of the composite film of the present embodiment can be appropriately selected according to the purpose and the like, but is generally about 5 to 500 μm, preferably about 50 to 200 μm.

The composite film of this embodiment can be used as it is, but it can also be used as an adhesive sheet by forming an adhesive layer on one or both sides. It does not specifically limit as an adhesive composition, A general thing, such as an acryl type and a rubber type, can be used. The method of forming the pressure-sensitive adhesive is not particularly limited, and a method of directly applying a solvent-based or emulsion-based pressure-sensitive adhesive to a composite film and drying it, applying these pressure-sensitive adhesives to a release paper, and pre-adhesive layer And a method of sticking the pressure-sensitive adhesive layer to the composite film can be applied. A method can also be applied in which a radiation curable pressure-sensitive adhesive is applied to a composite film, and both the pressure-sensitive adhesive layer and the film are irradiated with radiation to simultaneously cure and form the composite film and the pressure-sensitive adhesive layer. In this case, the pressure-sensitive adhesive layer and the composite film layer can be applied so as to have a multilayer structure.

The thickness of the pressure-sensitive adhesive layer is not particularly limited and can be arbitrarily set. Usually, it is preferably 3 to 100 μm, more preferably 10 to 50 μm, particularly about 10 to 30 μm. It is preferable that

The composite film in the present embodiment can be laminated with another film on one side or both sides. Examples of materials for forming other films include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene (PE) and polypropylene (PP), polyimide (PI), and polyetheretherketone (PEEK). In addition to thermoplastic resins such as polyvinyl chloride (PVC), polyvinylidene chloride resins, polyamide resins, polyurethane resins, polystyrene resins, acrylic resins, fluorine resins, cellulose resins, polycarbonate resins, etc., thermosetting Resin etc. are mentioned. The other film may have a single layer structure, but may be a film having a multilayer structure composed of a plurality of layers made of the same or different materials.

The use of the composite film of the present embodiment is not particularly limited, and can be used as a film substrate or a protective film that can be applied to various uses such as home use, medical use, agricultural use, and industrial use.

Next, the present invention will be described in more detail based on examples. The present invention is not limited to these examples. In the following examples, unless otherwise specified, parts mean parts by weight and% means% by weight.

(Reference Example-Formation of Composite Film by Curing Standard Mixture)
In a reaction vessel equipped with a condenser, a thermometer, and a stirrer, 40 parts of isobornyl acrylate (hereinafter abbreviated as “IBXA”) as an acrylic monomer and n-butyl acrylate (hereinafter abbreviated as “BA”) ) As a polyol, 34.2 parts poly (oxytetramethylene) glycol (hereinafter abbreviated as “PTMG”; manufactured by Mitsubishi Chemical Corporation) having a number average molecular weight of 650, and dibutyltin dilaurate (hereinafter, “ 12.5 parts of hydrogenated xylylene diisocyanate (hereinafter abbreviated as “HXDI”; manufactured by Mitsui Chemicals Polyurethane Co., Ltd.) was added dropwise and stirred at 65 ° C. The urethane polymer was synthesized by reacting for a time to obtain a urethane polymer-acrylic monomer mixture. Thereafter, 3.0 parts by weight of hydroxyethyl acrylate (hereinafter abbreviated as “HEA”) is added, and the mixture is reacted at 65 ° C. for 1 hour to obtain a reference mixture A which is an acryloyl group-terminated urethane polymer-acrylic monomer mixture. It was. In addition, the usage-amount of the diisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.25.

To 100 parts by weight of the reference mixture A, 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name “Irgacure 651” manufactured by Ciba Specialty Chemical Co., Ltd.) (hereinafter “Irg”) was used as a photopolymerization initiator. .651 "))) was added to give 0.15 parts of the reference mixture A '.

The reference mixture A ′ was applied onto a 38 μm-thick polyethylene terephthalate (PET) subjected to a release treatment so that the thickness after curing was 100 μm to form a coating film. The coated PET film was overlaid on the coating film, and then the coated PET film surface was irradiated with ultraviolet rays (illuminance 9 mW / cm ² , light amount 1200 mJ / cm ² ) using a black light and a metal halide lamp. And cured to form a urethane-acrylic composite film on the PET film.

Example 1
To 100 parts by weight of the reference mixture A, as a photopolymerization initiator, Irg. Addition mixture A was obtained by adding 0.15 part of 651 and 0.1 part of thioglycolic acid (hereinafter abbreviated as “TGA”) as a chain transfer agent. In the same manner as in the Reference Example, a coating film was formed with the additive mixture A and radiation curing was performed to form a urethane-acrylic composite film.

(Example 2)
To 100 parts by weight of the reference mixture A, as a photopolymerization initiator, Irg. Addition mixture B was obtained by adding 0.15 part of 651 and 0.5 part of TGA as a chain transfer agent. In the same manner as in the Reference Example, a coating film was formed with the additive mixture B and radiation curing was performed to form a urethane-acrylic composite film.

(Example 3)
To 100 parts by weight of the reference mixture A, as a photopolymerization initiator, Irg. Addition mixture C was obtained by adding 0.15 part of 651 as a chain transfer agent and 1.0 part of TGA. In the same manner as in the Reference Example, a coating film was formed with the additive mixture C and radiation curing was performed to form a urethane-acrylic composite film.

(Comparative Example 1)

100 parts by weight of the reference mixture A, 5 parts of trimethylolpropane triacrylate (hereinafter abbreviated as “TMPTA”) as an acrylic monomer, and Irg. By adding 0.165 parts of 651, a reference mixture α in which the composition of the acrylic monomer was changed was obtained. In the same manner as in the reference example, a coating film was formed with the reference mixture α and radiation curing was performed to form a urethane-acrylic composite film.

(Comparative Example 2)
As the polyol, 35.0 parts by weight of poly (oxypropylene) glycol having a number average molecular weight of 700 (hereinafter abbreviated as PPG720; manufactured by Asahi Glass Urethane Co., Ltd., trade name “Exenol 720”) and 12.2 parts by weight of HXDI were dropped. The urethane polymer was synthesized by reacting at 65 ° C. for 5 hours to obtain a urethane polymer-acrylic monomer mixture. Thereafter, 2.9 parts by weight of HEA was further added and reacted at 65 ° C. for 1 hour to change the composition of the urethane polymer. The acryloyl group-terminated urethane polymer-acrylic system was the same as in the reference example. A reference mixture β, which is a monomer mixture, was obtained. In addition, the usage-amount of the diisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.25.

Into 100 parts by weight of the reference mixture β, as a photopolymerization initiator, Irg. The reference mixture β 'was obtained by adding 0.15 part of 651. In the same manner as in the reference example, a coating film was formed with the reference mixture β 'and radiation curing was performed to form a urethane-acrylic composite film.

<Evaluation test>
(Evaluation of mechanical properties)
With respect to the obtained composite film, as an evaluation of mechanical properties, the tensile strength at break, the stress at 20% elongation, and the elongation at break were measured based on the following evaluation methods.

That is, after the obtained composite film was cut into a width of 10 mm and a length of 130 mm, the separator was removed, and “Autograph-1kNG” (manufactured by Shimadzu Corporation) was used as a tensile tester to A tensile test was performed at a speed of 200 mm / min, a distance between chucks of 50 mm, and room temperature (23 ° C.) to obtain a stress-strain curve. The stress at the time when the composite film breaks is obtained to obtain the elongation breaking strength, and the stress per unit area when the film is stretched by 20% (when the distance between chucks is extended by 20% with respect to the initial distance between chucks) is 20%. It was set as the stress at the time of extension. Further, the rate of change (%) of the measured values of the example and the comparative example with respect to the measured value of the reference example is calculated by using the following formula, assuming that the value of the tensile fracture strength of the reference example and the stress at 20% elongation is 100%. did.
Rate of change = (each measured value of Examples and Comparative Examples / each measured value of Reference Example) × 100 (%)

In addition, after obtaining a stress-strain curve in the same manner as described above, the stress when the composite film breaks is obtained to obtain the elongation break strength, and the elongation rate when it is subsequently broken (the chuck at break relative to the initial distance between chucks) The ratio of the distance between them was defined as the elongation at break. Further, the rate of change (%) of the measured values of the example and the comparative example with respect to the measured value of the reference example was calculated using the following formula, assuming that the value of the elongation at break and the elongation at break of the reference example was 100%. .
Rate of change = (each measured value of Examples and Comparative Examples / each measured value of Reference Example) × 100 (%)

The abbreviations in the table are as follows.
PTMG: poly (oxytetramethylene) glycol having a number average molecular weight of 650 PPG720: poly (oxypropylene) glycol having a number average molecular weight of 700 HXDI: hydrogenated xylylene diisocyanate HEA: hydroxyethyl acrylate IBXA: isobornyl acrylate BA: n-butyl Acrylate AA: Acrylic acid TMPTA: Trimethylolpropane triacrylate Irg. 650: 2,2-dimethoxy-1,2-diphenylethane-1-one TGA: thioglycolic acid

As shown in Examples 1 to 3, the tensile strength at break of the urethane-acrylic composite film to which the chain transfer agent TGA was added was 89.8 to 105.0% of the tensile strength at break of the reference example. It was almost the same value. The stress at 20% elongation was 87.2 to 31.2% of the stress at 20% elongation of the reference example, which was lower than that of the reference example. On the other hand, in Comparative Example 1 in which the acrylic composition was changed, the tensile strength at break showed the same value as 105.5% of the reference example, but the stress at 20% elongation was 142.0% higher than that of the reference example. showed that. In Comparative Example 2 in which the urethane composition was changed, the stress at 20% elongation was 88.8%, which was lower than that of the reference example, but the tensile strength at break was 43.9% of the reference example. The value changed more greatly than the tensile strength at break. On the other hand, the elongation at break was 140.7 to 260.3% of the elongation at break of the reference example, which was higher than that of the reference example. On the other hand, in Comparative Example 1 in which the acrylic composition was changed, the tensile strength at break showed a value equivalent to 105.5% of the reference example, but the elongation at break was a low value of 79.8% relative to the reference example. showed that. Further, in Comparative Example 2 in which the urethane composition was changed, the elongation at break was 117.9% higher than that of the reference example, but the tensile strength at break was 43.9% of the reference example. The value changed more greatly than the tensile strength at break.

Claims

A method for producing a composite film comprising a urethane polymer and an acrylic polymer,
A reference mixture preparation step for preparing a reference mixture comprising the urethane polymer and at least one acrylic monomer;
An additive mixture preparation step of adding 0.01 parts by weight or more and 5 parts by weight or less of a chain transfer agent to 100 parts by weight of the reference mixture;
A composite film forming step of curing the additive mixture to form a composite film,
The elongation breaking strength S2 of the composite film P2 obtained by curing the additive mixture is a value of 85% to 115% of the elongation breaking strength S1 of the composite film P1 obtained by curing the reference mixture, and the composite film The stress M2 when the P2 is stretched by 20% is 90% or less of the stress M1 when the composite film P1 is stretched by 20%, or when the composite film P2 is stretched and broken. The elongation at break E2 is a method for producing a composite film having a value of 120% or more of the elongation at break E1 when the composite film P1 is stretched and broken.
The method for producing a composite film according to claim 1, wherein the urethane polymer contains an acryloyl group-terminated urethane polymer.
The method for producing a composite film according to claim 1 or 2, wherein, in the reference mixture preparation step, the urethane polymer is formed by a reaction between a polyol and an isocyanate in the presence of the at least one acrylic monomer.
In the composite film forming step, the radiation-curable additive mixture is applied onto a substrate to form a coating film, and the coating film is irradiated with radiation to be cured to form a composite film. The manufacturing method of the composite film of any one of these.
A composite film obtained by the method for producing a composite film according to any one of claims 1 to 4.