JP2007160740A - Method and device for manufacturing eva film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for manufacturing high-quality EVA film with a high yield by avoiding defective products due to crosslinkage of the EVA resin under processing in manufacturing EVA film by calendering an EVA resin composition containing a crosslinking agent. <P>SOLUTION: When the EVA film is manufactured by calendering the EVA resin composition containing the crosslinking agent, the temperature of a rolled sheet on a mixed roll or/and a calender roll is measured, and the measurement result is monitored to control the temperature so that the temperature becomes lower than the crosslinking temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for producing an EVA (ethylene-vinyl acetate copolymer) film, and in particular, when producing an EVA film by calendering of an EVA resin composition containing a crosslinking agent, The present invention relates to a method and an apparatus for producing a high-quality EVA film with high yield by preventing generation of defective products due to crosslinking.

  EVA film is excellent in transparency and adhesiveness, so it can be used for bonding functional films such as laminated glass interlayer film, solar cell sealing film, anti-reflection film, etc. to the front filter of PDP (plasma display). Widely used as an intermediate film or the like.

  As a method for forming an EVA film used for these various uses, a method by calendering has been proposed (Japanese Patent Laid-Open No. 2000-84967).

  The calender is made up of a group of several rolls, and is a machine for producing a sheet-like product by applying a shear deformation to the molten resin by the rotation of the roll and extending it. FIG. 1 shows an example of a general calendar processing facility.

  The raw material 10 kneaded by the kneader 11 is fed to the kneading roll 13 by the conveyor 12 and further conveyed to the calendar 15 by the conveyor 14. That is, since the calender simply rolls the raw material, a blender roll, a Banbury mixer, an open mill, or the like is used to plasticize the raw material as a pre-process. In the calendar 15, the raw material resin is thinly rolled between the calendar rolls 15 </ b> A to 15 </ b> D, peeled off by the take-off roll 16, cooled by the cooling roll 18, and then the film 20 is taken up by the winder 19. When it is necessary to perform uneven processing on the film surface, embossing is performed by the embol roll 17 after the take-off roll 16.

  Conventionally, as shown in FIGS. 2 (a) to 2 (g), various types of calendar roll arrangements have been provided and used according to the purpose (in FIGS. 2 (a) to (g)). 10 is a raw material, 15A to 15E are calendar rolls, and 20 is a film.

Conventionally, as an EVA resin raw material for producing an EVA film, an EVA resin composition containing a crosslinking agent for the purpose of improving adhesiveness and durability has been used. As this crosslinking agent, an organic peroxide that generates radicals at 100 ° C. or higher is generally used.
JP 2000-84967 A

  When forming an EVA film by calendering of the EVA resin composition, the sheet to be rolled is caused by the frictional heat between the milled roll and the roll on the calender roll, the kneaded roll and the calender roll by the rotation of the kneading roll and the calender roll. Is heated and the sheet temperature rises. That is, in calendering, the kneading roll and calender roll used for processing are controlled so as to have a preset temperature, but the sheet to be rolled on the kneading roll and the calender roll is not necessarily kneading roll and calender roll. In some cases, the sheet to be rolled has a temperature higher than the set temperature of the kneading roll and the calender roll due to friction between the kneading roll and the calender roll and the sheet to be rolled.

  The heat of friction caused by the friction between the sheet to be rolled, the kneading roll, and the calender roll becomes higher as the rotation speed of the kneading roll and the calender roll is higher.

  And, when a raw material EVA resin composition contains a cross-linking agent, this rolled sheet is heated to a temperature equal to or higher than the cross-linking temperature of the EVA resin (that is, the radical generation temperature of the organic peroxide), The EVA resin in the sheet to be rolled during calendar processing may cause a crosslinking reaction. When the EVA resin causes a crosslinking reaction, the EVA film can no longer be used as an adhesive film or the like. Therefore, the EVA film that has undergone the crosslinking reaction is discarded as a defective product.

  Conventionally, the temperature of the rolled sheet during calendar processing has not been monitored, and measures such as lowering the processing temperature after the rolled sheet starts to undergo a crosslinking reaction have resulted in the occurrence of defective products. Could not be prevented.

  The present invention solves the above-mentioned conventional problems, and when producing an EVA film by calendering of an EVA resin composition containing a cross-linking agent, prevents occurrence of defective products due to cross-linking of the EVA resin during processing, resulting in high quality A method and an apparatus for producing an EVA film having a high yield are manufactured.

  In the production method of the EVA film of the present invention (Claim 1), when the EVA film is produced by calendering the EVA resin composition containing a crosslinking agent, the sheet to be rolled on the kneading roll and / or on the calender roll. The temperature is measured, the measurement result is monitored, and the temperature is controlled so that the temperature is lower than the crosslinking temperature of the EVA resin.

  The method for producing an EVA film of claim 2 is characterized in that, in claim 1, the temperature of the rolled sheet on the kneading roll and / or the calender roll is measured with a non-contact thermometer.

  According to a third aspect of the present invention, there is provided a method for producing an EVA film according to the first or second aspect, wherein the temperature control is performed by changing a rotation speed of the kneading roll and / or the calender roll.

  The method for producing an EVA film of claim 4 is characterized in that, in any one of claims 1 to 3, the temperature control is performed by water cooling the kneading roll and / or the calender roll.

  When the temperature of the to-be-rolled sheet on the kneading roll and / or the calender roll becomes higher than a predetermined temperature in the manufacturing method of the EVA film of claim 5 according to any one of claims 1 to 4 An alarm is issued, and the temperature control is performed based on the alarm.

  The method for producing an EVA film according to claim 6 is the method according to any one of claims 1 to 4, wherein the temperature of the sheet to be rolled on the kneading roll and / or the calender roll is higher than a predetermined temperature. The temperature control is automatically performed.

  The apparatus for producing an EVA film of the present invention (invention 7) is an apparatus for producing an EVA film by calendering an EVA resin composition containing a crosslinking agent, and a kneading roll for kneading the EVA resin composition and a calender roll for rolling. And a temperature measuring means for measuring the temperature of the sheet to be rolled on the kneading roll and / or the calendar roll, and the measurement result of the temperature measuring means is monitored, and the rolling is performed on the kneading roll and / or the calendar roll. And a monitoring unit that issues an alarm when the temperature of the seat becomes higher than a predetermined temperature.

  The apparatus for producing an EVA film according to claim 8 is an apparatus for producing an EVA film by calendering an EVA resin composition containing a cross-linking agent, wherein the kneading roll for kneading the EVA resin composition and the calender roll for rolling are kneaded. Temperature measuring means for measuring the temperature of the sheet to be rolled on the roll and / or calendar roll, and monitoring the measurement result of the temperature measuring means, the temperature of the sheet to be rolled on the kneading roll and / or the calendar roll is And an automatic control means for reducing the rotational speed of the kneading roll and / or the calendar roll when the temperature becomes higher than a predetermined temperature.

  An apparatus for producing an EVA film according to claim 9 is characterized in that, in claim 7 or 8, the temperature measuring means measures with a non-contact thermometer.

  According to the present invention, the temperature of the sheet to be rolled on the kneading roll and / or the calender roll is measured and the measurement result is monitored, and the temperature is controlled so that this temperature is lower than the crosslinking temperature of the EVA resin. Thus, the crosslinking reaction of the EVA resin during the calendar process can be surely prevented, and the occurrence of defective products due to the crosslinking reaction of the EVA resin can be prevented. Therefore, according to the present invention, a high-quality EVA film can be produced with a high yield.

  Embodiments of the EVA film manufacturing method and manufacturing apparatus of the present invention will be described in detail below.

  In the present invention, in producing an EVA film by calendering of an EVA resin composition containing a crosslinking agent, the temperature of the sheet to be rolled on the kneading roll and / or the calender roll is measured, and the measurement result is monitored. Is controlled to be lower than the crosslinking temperature of the EVA resin.

  Here, the temperature of the sheet to be rolled on the kneading roll and / or the calender roll is preferably measured from a non-contact thermometer from the viewpoint of not affecting the calendering. A system, a light temperature system, or the like can be used.

  The kneading roll and / or the calender roll for measuring temperature may be, for example, all of the kneading roll 13 and the calender rolls 15A to 15D in the calender roll processing facility shown in FIG. Only a calendar roll whose temperature tends to rise may be used. In a normal case, for example, it is preferable to measure the temperature of the sheet to be rolled on the calendar rolls 15B and 15C among the four calendar rolls 15A to 15D shown in FIGS.

  The temperature measurement of the sheet to be rolled on the kneading roll and / or the calender roll may be continuous measurement or intermittent measurement once every 1 to 10 minutes. This is preferable for reliably preventing the crosslinking reaction.

  When the temperature of the sheet to be rolled becomes higher than a predetermined temperature by measuring the temperature of the sheet to be rolled, temperature control is performed manually or automatically.

  This temperature control is performed by reducing the heat of friction by lowering the rotational speed of the kneading roll and / or calender roll that is measuring the temperature of the sheet to be rolled, or by cooling the kneading roll and / or calender roll with water. It can be performed by a method such as lowering the temperature, lowering the temperature with cooled oil, or air-cooling the rolled sheet.

  When the temperature is controlled manually by an operator, a monitoring device is provided to monitor the result of temperature measurement and issue an alarm when the temperature becomes higher than a predetermined temperature. It is preferable that the worker is informed of the temperature rise by virtue of i).

  In addition, when automatically controlling the temperature, the result of temperature measurement is monitored, and when the temperature becomes higher than a predetermined temperature, the number of rotations of the kneading roll and / or calendar roll is decreased, or the kneading roll It is preferable to provide an automatic control means for taking measures such as circulating water for water cooling on the calendar roll. In this case, it goes without saying that an alarm may be issued when the temperature becomes higher than a predetermined temperature.

  The predetermined temperature is a temperature at which the crosslinking reaction of the EVA resin can be surely prevented, and varies depending on the type of the crosslinking agent contained in the EVA resin composition, but includes, for example, an organic peroxide as the crosslinking agent. In this case, the temperature is preferably 5 to 10 ° C. lower than the temperature at which the organic peroxide decomposes to generate radicals, for example, about 90 to 95 ° C.

  In this way, the rotational speed of the kneading roll and / or the calender roll is reduced or the kneading roll and / or the calender roll so that the temperature of the rolled sheet on the kneading roll and / or the calender roll is lowered. When the temperature of the sheet to be rolled on the kneading roll and / or the calender roll is lowered by water cooling, and when the temperature falls to the set temperature of the kneading roll and / or the calender roll, the rotation speed of the kneading roll and / or the calender roll It is preferable to return to the original processing conditions by returning the rotational speed to the original rotational speed or stopping the water cooling. Thus, when returning to the original processing conditions, it can be performed manually or automatically as described above.

  Next, an EVA resin composition suitable as a film forming raw material according to the present invention will be described.

  The EVA resin according to the present invention preferably has a vinyl acetate content of 30% by weight or less. If the vinyl acetate content exceeds 30% by weight, the water vapor transmission rate is too high, and it is difficult to obtain sufficient moisture resistance as a sealing film for solar cells, an intermediate film for laminated glass, and the like. However, EVA resin with excessively low vinyl acetate content has poor processability and too high viscosity. For example, when manufacturing solar cells, the followability to silicon power generation elements is poor. The amount is preferably 10% by weight or more.

  The EVA resin used in the present invention preferably has a melt flow rate of 0.7 to 20, particularly 1.5 to 10.

  In order to improve durability, the EVA resin composition used in the present invention has a cross-linking structure by adding a cross-linking agent. Generally, as the cross-linking agent, an organic peroxide that generates radicals at 100 ° C. or higher is used. In particular, if the stability at the time of blending is taken into consideration, it is preferable that the decomposition temperature with a half-life of 10 hours is 70 ° C. or higher. Examples of such an organic peroxide include 2,5-dimethylhexane; 2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; -T-butyl peroxide; t-dicumyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne; dicumyl peroxide; α, α'-bis (t-butylperoxide Oxyisopropyl) benzene; n-butyl-4,4-bis (t-butylperoxy) butane; 2,2-bis (t-butylperoxy) butane; 1,1-bis (t-butylperoxy) cyclohexane 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane; t-butylperoxybenzoate; benzoyl peroxide, etc. it can. The compounding amount of these organic peroxides is generally 5 parts by weight or less, preferably 1 to 3 parts by weight with respect to 100 parts by weight of the EVA resin.

  Moreover, a silane coupling agent can be added to the EVA resin composition for the purpose of improving the adhesive force as a sealing film for solar cells, an intermediate film for laminated glass, or the like. Known silane coupling agents for this purpose are, for example, γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; γ-methacryloxy. Propyltrimethoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercaptopropyltrimethoxysilane; γ-aminopropyltrimethoxysilane N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane and the like can be mentioned. The amount of these silane coupling agents is generally 5 parts by weight or less, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the EVA resin.

  Furthermore, a crosslinking aid can be added to the EVA resin composition in order to improve the gel fraction of the EVA resin and improve the durability. Examples of crosslinking aids provided for this purpose include trifunctional crosslinking aids such as triallyl isocyanurate; triallyl isocyanate as well as monofunctional crosslinking aids such as NK esters. it can. The amount of these crosslinking aids is generally 10 parts by weight or less, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the EVA resin.

  Furthermore, hydroquinone; hydroquinone monomethyl ether; p-benzoquinone; methyl hydroquinone and the like can be added to the EVA resin composition for the purpose of improving the stability of the EVA resin. The amount of these compounds is generally 100 parts by weight of the EVA resin. The amount is 5 parts by weight or less.

  Furthermore, in addition to the above, a colorant, an ultraviolet absorber, an antiaging agent, a discoloration preventing agent and the like can be added to the EVA resin composition as necessary. Examples of the colorant include inorganic pigments such as metal oxides and metal powders, and organic pigments such as azo-based, phthalocyanine-based, additive-based, acidic or basic dye-based lakes. Examples of ultraviolet absorbers include 2-hydroxy-4-octoxybenzophenone; benzophenones such as 2-hydroxy-4-methoxy-5-sulfobenzophenone; 2- (2′-hydroxy-5-methylphenyl) benzotriazole Benzotriazoles; phenyl salsylates; hindered amines such as pt-butylphenyl salsylates. Antiaging agents include amines; phenols; bisphenyls; hindered amines, such as di-t-butyl-p-cresol; bis (2,2,6,6-tetramethyl-4-piperazyl). ) Sebacate.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
An EVA film was formed using an EVA resin composition having the following composition.
[EVA resin composition blend (parts by weight)]
EVA resin (vinyl acetate content 25% by weight, melt flow rate 2.0): 100
Cross-linking agent (cross-linking agent that generates radicals at 100 ° C.): 2.5
Silane coupling agent (methacryloxypropyltrimethoxysilane): 0.5
Crosslinking aid (triallyl isocyanurate): 2.0

As shown in FIG. 1, first, the EVA resin composition is obtained with a kneader 11 (60 ° C.), and this EVA resin composition is kneaded with a kneading roll 13 at 60 ° C., then calendered, and then embossed. Processed, cooled and wound up. This calendering was performed with the inverted L-shaped four calender rolls 15 (15A to 15D) shown in FIG. 2 (d), and the following conditions were adopted as the rotation speed and temperature of each roll.
<First roll 15A>
Rotation speed: 3rpm
Temperature: 70 ° C
<Second roll 15B>
Rotation speed: 4rpm
Temperature: 72 ° C
<Third roll 15C>
Rotation speed: 6rpm
Temperature: 80 ° C
<Fourth roll 15D>
Rotation speed: 7rpm
Temperature: 80 ° C

  At this time, the temperature of the rolled sheet on the second roll 15B was continuously measured and monitored with a non-contact thermometer ("Radiation Thermometer IT2-50" manufactured by Keyence Corporation). Since the EVA resin of the EVA resin composition used causes a crosslinking reaction when the temperature reaches 100 ° C., when the measurement temperature reaches 95 ° C., the number of rotations of this roll is automatically reduced to 3 rpm, and this temperature decreases to 90 ° C. Then, when automatic control was performed again to restore the original rotational speed, no defective product due to the cross-linking reaction during calendering occurred, and an EVA film could be produced with a yield of 100%.

It is a schematic diagram explaining the film forming method of a calendar process. It is a schematic diagram which shows a general calendar roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Kneading machine 13 Kneading roll 15 Calendar 15A, 15B, 15C, 15D, 15E Calendar roll 16 Take-off roll 17 Embossing roll 18 Cooling roll 19 Winding machine

Claims (9)

  In producing an EVA film by calendering an EVA resin composition containing a crosslinking agent, the temperature of the sheet to be rolled on the kneading roll and / or the calender roll is measured, and the measurement result is monitored. A method for producing an EVA film, characterized in that the temperature is controlled to be lower than a crosslinking temperature of the EVA resin.   The method for producing an EVA film according to claim 1, wherein the temperature of the rolled sheet on the kneading roll and / or the calendar roll is measured with a non-contact thermometer.   3. The method for producing an EVA film according to claim 1, wherein the temperature control is performed by changing a rotation speed of the kneading roll and / or the calender roll.   The method for producing an EVA film according to any one of claims 1 to 3, wherein the temperature control is performed by water cooling the kneading roll and / or the calender roll.   In any 1 item | term of the Claims 1 thru | or 4, when the temperature of the to-be-rolled sheet on the said kneading roll and / or a calender roll becomes higher than predetermined | prescribed temperature, a warning is issued, Based on this warning, the said temperature An EVA film manufacturing method characterized by performing control.   In any one of Claims 1 thru | or 4, when the temperature of the to-be-rolled sheet on the said kneading roll and / or a calender roll becomes higher than predetermined | prescribed temperature, performing the said temperature control automatically. The manufacturing method of the characterized EVA film. In an apparatus for producing an EVA film by calendering an EVA resin composition containing a crosslinking agent,
A kneading roll for kneading the EVA resin composition and a calender roll for rolling;
Temperature measuring means for measuring the temperature of the sheet to be rolled on the kneading roll and / or the calendar roll;
And monitoring means for monitoring the measurement result of the temperature measuring means and issuing an alarm when the temperature of the rolled sheet on the kneading roll and / or the calender roll becomes higher than a predetermined temperature. An EVA film manufacturing apparatus characterized by the above. In an apparatus for producing an EVA film by calendering an EVA resin composition containing a crosslinking agent,
A kneading roll for kneading the EVA resin composition and a calender roll for rolling;
Temperature measuring means for measuring the temperature of the sheet to be rolled on the kneading roll and / or the calendar roll;
The measurement result of the temperature measuring means is monitored, and when the temperature of the rolled sheet on the kneading roll and / or the calender roll becomes higher than a predetermined temperature, the number of rotations of the kneading roll and / or the calender roll An EVA film manufacturing apparatus, comprising: an automatic control means for lowering the pressure.   9. The EVA film manufacturing apparatus according to claim 7, wherein the temperature measuring means measures with a non-contact thermometer.

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