JP3319036B2 - Film laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film laminate. More specifically, when forming a thermal recording medium for video printers, plotting paper for drafting, printing paper, ink jet paper, thermal transfer recording paper, etc., a water-soluble or water-dispersible aqueous coating liquid is used as a support for them. It relates to a film laminate particularly suitable for application.

[0002]

2. Description of the Related Art A plastic film such as a thermoplastic polyester film or a polypropylene film has a high cohesive force on its surface and is poor in acceptability of paints, inks and the like.
In particular, since the surface is hydrophobic, it has poor wettability with an aqueous polymer substance and the like, and has poor adhesion. For this reason, when attempting to apply a coating liquid containing an aqueous polymer substance, repelling frequently occurs, and even if coating is possible, the adhesion between the coating film and the film surface is poor and the coating film is easily peeled off from the film surface. Will fall off.

In order to solve this problem, for example, a method of applying a corona discharge treatment to the film surface to improve the wettability between the surface of the polypropylene and the synthetic resin layer and to strengthen the adhesiveness (Japanese Patent Publication No. 48-48) -29316), a method of performing a corona discharge treatment in a nitrogen or other gas atmosphere (Japanese Patent Publication No. 24855/1995), an ultraviolet irradiation treatment, a plasma treatment, and a flame treatment to activate the film surface, and then a synthetic resin layer is formed. Is applied.

Indeed, these film surface activating means can be expected to improve wettability and adhesiveness with an increase in bonding strength. However, there is the disadvantage that the activity thus obtained decreases over time. Therefore, the means for activating the film surface described above is not always satisfactory. As another method for improving the receptivity of the film surface, there is an etching method in which the surface is dissolved and swollen with various chemicals or partially dissolved. This involves contacting the film surface with an acid, alkali, amine salt, trichloroacetic acid, phenols, etc., etching the film surface, decomposing and dissolving the crystal orientation near the surface, and simultaneously reducing the cohesiveness and reducing the binder. The purpose is to enhance the adhesiveness with the resin.

[0005] However, some chemicals used in this method involve danger in handling. Also,
There are various problems in practical use, such as the possibility that volatiles of the drug may be released into the atmosphere, and that care must be taken to prevent contamination of the working environment. As a method similar to the etching method described above, there is a method in which a surface layer (primer layer) different from the base film is formed on the film surface in advance, and then a target coating solution is formed.

For example, a method of improving adhesion by forming a primer layer (primer treatment) on a polyester film surface is often achieved by applying a coating solution dissolved in an organic solvent to the film surface. Such a method causes environmental pollution, safety and hygiene problems due to the organic solvent during the production, and may adversely affect the production process. Therefore, the use of the organic solvent must be minimized.

Therefore, when a primer layer is to be formed on a film surface, it is most preferable to use a composition using water as a solvent from the viewpoint of process, economy and safety. Such primer compositions using water as a medium have been conventionally proposed. For example, Japanese Patent Publication No. 46-10193 discloses a polyurethane having dispersibility in acetone and water dispersibility. JP-A-61-233
No. 539 discloses a primer composition obtained by crosslinking an aqueous polyurethane having a carboxylate or the like with aqueous melamine. JP-A-63-118249 discloses a primer layer containing an aqueous vinylidene chloride resin as a main component.

[0008] The wettability and adhesion are improved by applying a substance which reacts with a slight amount of the surface functional group to the film on which these primer layers are laminated. However, since all of these treatment liquids use a crosslinking reaction to firmly adhere to the film surface, the crosslinking reaction is often insufficient immediately after application, and the adhesion to the film surface is poor. Sufficient and easy to peel off. In order to prevent this, it is necessary to leave the device for a certain period of time until a strong adhesive force is generated before use. Therefore, it is not suitable for high-speed production. Even in the case of an aqueous medium, it is necessary to use an organic solvent having high solubility in water such as alcohol and acetone together with water in order to improve the wettability with the film surface.

[0009]

As described above, in the conventional method, since the surface of the formed primer layer is insufficiently hydrophilized, the wettability with a coating solution containing a hydrophilic coating material, an aqueous ink, an aqueous emulsion, or the like is poor. However, there was a problem that the formation of the primer layer caused environmental problems and occupational health problems, and it was difficult to obtain a uniform primer layer having sufficient adhesion to the film surface. An object of the present invention is to solve the above-mentioned problems and to provide a film laminate having a primer layer that has sufficient adhesion to the film surface and has good wettability with various aqueous coating solutions. I do.

[0010]

The film laminate according to the present invention is a film laminate in which a primer layer containing polyethyleneimine, an aqueous synthetic resin and a starch- based adhesive is formed on at least one surface of a film sheet . ,
Film sheet (excluding polyester film)
Polyethyleneimine, aqueous synthetic tree on at least one side
Plastics containing fats and cellulose-based or starch-based adhesives
It is a film laminate on which an immer layer is formed. Further, it is preferable that the cellulose-based or starch-based adhesive is contained in the range of 0.1% by weight to 40% by weight based on the total solid content of the primer layer.

[0011]

The plastic film is generally formed into a sheet by melt-stretching uniaxially or biaxially. Further, the film is produced by adding a small amount of an antistatic agent for preventing static electricity during film forming, or adding a plasticizer, a pigment and the like for improving workability. However, when an aqueous coating solution is applied to these films, the plasticizer, antistatic agent, and surfactant in the resin may precipitate on the film surface over time, and the hydrophilicity of the film surface may vary, and cissing may occur. Occurs. For this reason, even if an attempt is made to form a uniform coating layer with a coating composed of an aqueous coating solution for forming a heat-sensitive recording layer, a uniform coating layer cannot be obtained stably due to a change in surface hydrophilicity with time. .

The present inventors have conducted intensive studies in order to solve these problems during film surface processing, and as a result, after forming a primer layer on the film surface with a specific aqueous coating solution containing no organic solvent, It has been found that a coating layer such as a heat-sensitive recording layer may be formed. With a medium system containing only water, it is conventionally common knowledge to form a primer layer that imparts hydrophilicity uniformly to a film surface that is essentially inferior in hydrophilicity, and that significantly improves adhesion to the film surface. , Seemed impossible.

However, in the present invention, the inventors overturned the common sense by including polyethyleneimine, an aqueous synthetic resin and a cellulose-based or starch-based adhesive in an aqueous paint for forming a primer layer, and contained only water. It has been found that, depending on the medium system, it is possible to form a primer layer that imparts hydrophilicity uniformly to a film surface that is originally poor in hydrophilicity and that significantly improves the adhesion to the film surface. Of course, the same effect was obtained by using a cellulose-based and a starch-based polymer adhesive together.

When a coating layer such as a heat-sensitive recording layer is formed thereon, a primer layer which does not generate cissing or the like and has strong adhesion to the formed coating layer is provided. It was found to be a film laminate. The aqueous coating for forming a primer layer used in the present invention contains an aqueous solution of polyethyleneimine.

[0015] The polyethyleneimine used in the present invention is an oligomer, which can be cross-linked three-dimensionally by heating in a drying step for forming a primer layer. In the past, depending on the coating method, the phenomenon that the resin constituting the primer layer was dissolved and the adhesion between the coating layer and the primer layer was reduced was observed. Such a phenomenon no longer occurs. That is, there is a property that the resin constituting the film surface and the primer layer is hardly dissolved in water. Further, advantageously, the crosslinking reaction does not change over time and exhibits stable adhesion.

However, polyethyleneimine binds firmly to functional groups such as carbonyl groups on the film surface.
The low molecular weight component remains and tends to be sticky. In particular,
During the production of the film roll, a large tension is applied and the film roll is strongly suppressed. Therefore, if polyethyleneimine is contained in the primer layer, the film surface and the film substrate back surface may be firmly adhered (blocking).

Therefore, the inventors have found that blocking can be controlled by including a water-soluble or water-dispersible aqueous synthetic resin in a primer layer containing polyethyleneimine. This synthetic resin includes various latexes such as polyvinyl alcohol, styrene butadiene copolymer, styrene acrylate copolymer, and methacrylate copolymer, which are non-adhesive synthetic polymer materials, and vinyl acetate crotonic acid. There are copolymer resins and the like. These synthetic polymer materials have a styrene component as a main component or a component such as a methyl ester as a main component in order not to have tackiness.

The degree to which these aqueous synthetic resins have no tackiness is 10 degrees or more, preferably 30 degrees or more in terms of glass transition point. However, simply using polyethyleneimine and an aqueous synthetic resin in combination may result in insufficient wettability to the film surface, which may cause cissing when applying an aqueous paint for forming a primer layer.

Therefore, in the present invention, a polymer adhesive having glucose, more specifically, oxidized starch, etherified starch, which is a cellulose-based or starch-based adhesive,
The use of at least one or a combination of esterified starch, natural starch, carboxymethylcellulose, and methylcellulose significantly improves the wettability to the film surface.

Further, in addition to the aqueous synthetic resin and the polymer adhesive having glucose, in order to improve the blocking, a material having a releasing property, for example, a wax mainly composed of polyolefin hydrocarbon, polyethylene , A water-dispersed emulsion such as polypropylene, silicone, a releasing agent containing a fluorine atom as a main component, and a fatty acid metal soap.

Various surfactants can be mixed in for the purpose of assisting the wettability to the film surface. Such a surfactant reduces the surface tension of the water-based paint for forming a primer layer by 4%.
A substance that can be reduced to 0 dyn / cm or less is preferable. Examples of the surfactant include polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate, alkyl sulfosuccinate, and quaternary ammonium. Salt chloride, alkylamine hydrochloride, and the like.

Further, as long as the effects of the present invention are not lost,
Antistatic agents, ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricants, antiblocking agents, and the like can be added. In particular, pigments, organic fillers, and waxes, which are granular components, may be added in a very small amount for the purpose of improving the processability such as embracing air during the production of a film roll.

The amount of polyethyleneimine in the primer layer of the present invention is from 5% to 50% based on the total solid content of the primer layer, and the amount of the aqueous synthetic resin used in combination is from 20% to 9%.
0% and cellulosic or starch based adhesives range from 0.1% to 40%. If the polyethyleneimine content is 5% or less, the adhesion to the film support may be poor, and if it is 50% or more, blocking occurs during production. Further, when the cellulose-based or starch-based adhesive is 40% or more, when a water-based coating solution such as a heat-sensitive recording material is applied on the film laminate of the present invention, the primer layer is eluted, and Adhesion with the surface cannot be obtained. In the present invention, unless otherwise specified, it is% by weight and part by weight.

The cellulose-based or starch-based adhesive is
In the present invention, there is a great effect in improving the wettability with the film surface. Surprisingly, even with a very small mixing ratio of 0.1%, repelling caused by poor wettability with the film surface is achieved. It was possible to prevent occurrence. This is supposedly because a cellulose-based or starch-based adhesive, which originally has poor wettability with the film, specifically hydrophilizes the hydrophobic portion of the polyethyleneimine solution.

The application of the water-based paint for forming the primer layer on the film surface may be carried out simultaneously with the usual application step, that is, the film stretching step. Further, a stretching step and a step of applying after cutting off may be used. However, in the stretching step and the application step performed by cutting away, dust is involved and the cost is low, so care must be taken to apply in a clean atmosphere. Further, in order to further enhance the adhesion of the primer layer to the film, it is more preferable to subject the film surface to corona discharge treatment and etching treatment in advance.

From this viewpoint, one side of the film or
A primer layer is formed on both sides. The solid content of the water-based paint for forming a primer layer is usually 10% or less, more preferably 5% or less, and the coating amount is 0.01 g / m ² to 2 g / m ² . The film laminate obtained as described above is also used as a support for magnetic tapes, floppy disks, X-ray photographic films and the like.

As the coating method, any known method can be applied. For example, a roll coater, a gravure coater,
Roll brush, spray coat, air knife coat, impregnation coat, curtain coat, etc. may be applied alone or in combination.

[0028]

【Example】

Example 1, Example 2, Example 3, Example 4 On the surface of a polypropylene film having a thickness of 60 μm (this film has not been subjected to corona treatment or the like in advance), each of the following: 0.1 g of a coating liquid for forming a primer layer having a composition (all in dry weight ratio)
/ M ² with a Mayer bar.

Example 1 Polyethyleneimine (Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.) solid concentration 30% 130 parts Styrene butadiene latex (glass transition point 30 degrees) Solid concentration 50% 160 parts Methyl cellulose (2% aqueous solution) ) 50 parts 4700 parts water

Example 2 Polyethyleneimine (Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.) solid content 30% 30 parts Styrene butyl acrylate latex (glass transition point 40 degrees) Solid concentration 50% 200 parts Methyl cellulose (2% Aqueous solution) 25 parts water 4750 parts

Example 3 Polyethyleneimine (Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.) solid content 30% 130 parts Styrene butadiene latex (glass transition point 30 degrees) Solid content 50% 160 parts Oxidized starch (10% Aqueous solution) 200 parts water 4500 parts

Example 4 Polyethyleneimine (Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.) solid content 30% 130 parts Styrene butadiene latex (glass transition point 30 degrees) Solid concentration 50% 160 parts Carboxymethyl cellulose (10% Aqueous solution) 10 parts water 4700 parts

Comparative Example 1 A primer layer was formed in the same manner as in Example 1 except that only polyethyleneimine was used. Comparative Example 2 A primer layer was formed in the same manner as in Example 1 except that polyethyleneimine and styrene-butadiene latex were used.

Comparative Example 3 Instead of forming the above-mentioned coating layer, the surface of the film support was subjected to corona discharge treatment in the same manner as in the example to form a primer layer. [Comparative Example 4] A polyethyleneimine aqueous dispersion was diluted with methyl alcohol by 30% to prepare a coating solution, and a coating film as a primer layer was formed on the film surface in the same manner as in Example 1.

[Method of Characteristic Evaluation] The following items were evaluated. (1) Wettability: The occurrence of repelling when a paint for forming a primer layer was applied to the surface of the polypropylene film was evaluated. The occurrence status was evaluated by the number of occurrences of repelling. 0 per 1 m ² ◎ 未 満 Less than 10 〇 １０ 10 or more △ Hazyk on the entire surface × 〇 or more is a usable repelling level.

(2) Adhesion: A cellophane tape was adhered to the surface of the produced film laminate, and a sharp peeling was performed to observe and evaluate how much the primer layer on the surface was peeled off. No peeling 〇 Sporadic peeling △ The whole is completely peeled off 〇 〇 or more is a usable adhesion level.

(3) Adhesion (blocking): The surface of the primer layer and the surface of the substrate of another film were overlapped and pressed at a pressure of 10 kg / cm 2, and the state of peeling was observed. Does not adhere at all and peels easily. 〇 Adheres but can peel. △ Cannot peel (primer layer peels off). × 〇 or more is a usable tackiness (blocking) level. The results of the above evaluation tests are shown in Table 1 below.

[0038]

[Table 1]

[Evaluation Results] In Example 3, very good wettability was shown, probably because of the large amount of starch-based adhesive compared to the other examples. In contrast to Example 1, it was found that repelling and blocking were insufficient with only polyethylene imine as in Comparative Example 1. Comparative Example 2 shows that cissing occurs when no cellulose-based adhesive is contained. Comparative Example 3
From this, it can be seen that when the primer layer is formed by corona discharge as described in JP-B-48-29316, the adhesion and the wettability are not yet sufficient. From Comparative Example 4, it can be seen that when the primer layer was formed by dissolving only polyethyleneimine in an organic solvent, the adhesion was still insufficient and the adhesion was poor.

An aqueous thermosensitive recording material coating was applied to each of the film laminates on each of which the primer layer was formed in each of the above Examples, and the occurrence of cissing was observed. In each of the examples, only 0 to less than 10 cissings were observed per 1 m ² , showing very excellent wettability.

The film laminate thus obtained is used as a support for forming a thermal recording medium for a video printer, plotting paper for drawing, printing paper, ink jet paper, thermal transfer recording paper, etc. It is a film laminate particularly suitable for applying a water-soluble or water-dispersible aqueous coating liquid. Further, as a support suitable for another aqueous coating process, a plastic film laminate suitable for use as a support such as a magnetic tape, a floppy disk, and an X-ray photographic film can be obtained.

[0042]

The film has good wettability with various aqueous coating liquids including hydrophilic paints, water-based inks, water-based emulsions and the like. It is a film laminate having a uniform primer layer with excellent adhesion.

Claims (5)

(57) [Claims] 1. A film laminate in which a primer layer containing polyethyleneimine, an aqueous synthetic resin and a starch- based adhesive is formed on at least one side of a film sheet. 2. The film laminate according to claim 1, wherein the starch- based adhesive is contained in the range of 0.1% by weight to 40% by weight based on the total solid content of the primer layer. 3. A film sheet (a polyester film)
At least one side of
, Water-based synthetic resin and cellulose or starch-based
A film laminate on which a primer layer containing an adhesive is formed. 4. The method according to claim 1, wherein the cellulose-based or starch-based adhesive is
0.1% by weight to 40% based on the total solid content of the primer layer
The film laminate according to claim 3, which is contained in a range of weight%. 5. The film sheet is a polypropylene film.
The film laminate according to any one of claims 1 to 4,
body.