JP2018077127A - Method for inspecting fiber sheet, prepreg, method for manufacturing prepreg, and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inspecting a fiber sheet, capable of preventing the fray of a fiber from occurring and appropriately determining whether or not the fiber sheet is appropriately used for manufacturing a prepreg having an undesired variation of thickness effectively prevented.SOLUTION: In the method for inspecting a fiber sheet used for impregnating varnish to manufacture a prepreg and an ear part treated by a fray prevention agent having the function of preventing a fiber from being frayed comprises: leaving a piece of the ear part of the fiber sheet on the surface of an inspection liquid having a kinetic viscosity of 10 mm/s or more and 1000 mm/s or less at 25°C and a surface tension of 15 mN/m or more and 40 mN/m or less; and determining the quality of the fiber sheet by a period of time until the piece sinks.SELECTED DRAWING: None

Description

  The present invention relates to a fiber sheet inspection method, a prepreg, a prepreg manufacturing method, and a laminate.

  A prepreg obtained by impregnating a fiber sheet with varnish is widely used (see, for example, Patent Document 1).

  In the fiber sheet used for manufacturing the prepreg, when the fibers are frayed, the productivity of the prepreg may be reduced due to the influence of the frayed fibers, or the apparatus used for manufacturing the prepreg may be adversely affected. Moreover, the productivity and reliability of the molded body using the prepreg may be adversely affected.

  In order to prevent the occurrence of such a problem, a fiber sheet used for manufacturing a prepreg is generally provided with an ear that has been subjected to a treatment for preventing fiber fraying.

  However, conventionally, prepregs manufactured using fiber sheets may have an undesired thickness variation. Such variations in thickness cause problems such as poor loading when a plurality of prepregs are stacked on the mounting table, and uneven press pressure when the prepreg is pressed.

JP 2013-129827 A

  An object of the present invention is to provide a prepreg in which fiber fraying hardly occurs and unintentional thickness variation is effectively prevented, and a prepreg manufacturing method capable of efficiently manufacturing the prepreg. , To provide a fiber sheet inspection method capable of appropriately determining whether or not the prepreg can be suitably used, and to provide a highly reliable laminate manufactured using the prepreg There is to do.

Such an object is achieved by the present inventions (1) to (12) below.
(1) A method for inspecting a fiber sheet impregnated with a varnish and used for producing a prepreg,
The fiber sheet is provided with an ear that has been treated with a fray-preventing agent having a function of preventing fiber fraying,
The section of the ear part of the fiber sheet is placed on the surface of the test liquid having a kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m to 40 mN / m. A method for inspecting a fiber sheet, wherein the quality of the fiber sheet is determined based on a time from when the section is allowed to stand to rest on the surface of the inspection liquid until the section is settled.

  (2) The fiber sheet is determined to be a non-defective product when the time from the resting of the section on the surface of the test liquid to the settling of the section is 20 seconds or more and 37 seconds or less. The fiber sheet inspection method according to (1) above.

(3) the area of the sections, 1 mm ² or more 200000 mm ² or less above (1) or (2) fiber sheet inspection method according to.

(4) A prepreg comprising a fiber sheet and a resin material impregnated in the fiber sheet,
The fiber sheet is provided with an ear that has been treated with a fray-preventing agent having a function of preventing fiber fraying,
The section of the ear part of the fiber sheet is placed on the surface of the test liquid having a kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m to 25 mN / m. A prepreg characterized by having a time from 20 seconds to 37 seconds after the section is left standing on the surface of the test liquid when it is left standing.

  (5) The prepreg according to (4) above, wherein the fiber sheet main body constituting the fiber sheet is a glass cloth.

  (6) The prepreg according to the above (4) or (5), wherein the fraying inhibitor contains at least one of a urethane resin and an acrylic resin.

  (7) The prepreg according to any one of (4) to (6), wherein the inspection liquid is dimethyl silicone.

  (8) The prepreg according to (7) above, wherein the dimethyl silicone has a weight average molecular weight of 6000 or more and 10,000 or less.

  (9) Said (4) thru | or (8) which the said resin material contains the 1 type (s) or 2 or more types selected from the group which consists of an epoxy resin, a phenol resin, cyanate resin, a maleimide resin, a melamine resin, and a urethane resin The prepreg according to any one of the above.

(10) A fiber sheet preparation step of preparing a fiber sheet including an ear portion that has been treated with a fraying inhibitor having a function of preventing fiber fraying;
An impregnation step of impregnating the fiber sheet with a varnish containing a resin material;
A semi-curing step of semi-curing the resin material,
As the fiber sheet, the surface of the liquid for inspection having a kinematic viscosity at 25 ° C. of 10 mm ² / s or more and 1000 mm ² / s or less and a surface tension of 15 mN / m or more and 30 mN / m or less as the fiber sheet. When the prepreg is allowed to stand, a prepreg having a time from 20 seconds to 37 seconds after the section is allowed to settle on the surface of the test liquid is used. Method.

  (11) The method for producing a prepreg according to the above (10), wherein the varnish contains at least one selected from the group consisting of acetone, methyl ethyl ketone, and dimethylformamide as a solvent.

  (12) A laminate in which a plurality of the prepregs according to any one of (4) to (9) are laminated, and the prepregs are bonded together by a cured product of the resin material.

  According to the present invention, it is possible to provide a prepreg in which fiber fraying hardly occurs and unintentional thickness variation is effectively prevented, and a prepreg manufacturing method capable of efficiently manufacturing the prepreg. , To provide a fiber sheet inspection method capable of appropriately determining whether or not the prepreg can be suitably used, and to provide a highly reliable laminate manufactured using the prepreg can do.

It is a longitudinal cross-sectional view which shows an example of a structure of a fiber sheet typically. It is a longitudinal cross-sectional view which shows an example of a structure of a prepreg typically. It is a longitudinal cross-sectional view which shows typically suitable embodiment of the manufacturing method of the prepreg of this invention. It is a longitudinal cross-sectional view which shows typically the structure of the prepreg manufacturing apparatus which can be used suitably for manufacture of the prepreg of this invention. It is a longitudinal section showing a suitable embodiment of a layered product of the present invention typically.

Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<< Outline of the Invention >>
FIG. 1 is a longitudinal sectional view schematically showing an example of the configuration of the fiber sheet, and FIG. 2 is a longitudinal sectional view schematically showing an example of the configuration of the prepreg.

  A fiber sheet 10 shown in FIG. 1 is composed of a plurality of fibers 1, and ears 2 are provided at both edges in the width direction.

The ear | edge part 2 is a site | part where the fraying prevention process of the fiber 1 by the fraying prevention agent 21 was performed.
The ear part 2 may contain air bubbles (not shown).

The prepreg 100 is obtained by impregnating the fiber sheet 10 with varnish.
As a result, the resin material (semi-cured material) 20 ′ enters (impregnated) the gaps (voids) between the fibers 1 constituting the fiber sheet 10, and the resin material (semi-cured material) 20 ′ adheres around the fibers 1. It has a structure (see FIG. 2).

  By the way, in the past, in the prepreg using the fiber sheet provided with the ear | edge part, the dispersion | variation in unintentional thickness may arise. Such variations in thickness cause problems such as poor loading when a plurality of prepregs are stacked on the mounting table, and uneven press pressure when the prepreg is pressed.

  Therefore, the present inventor paid attention to the fiber sheet used in the manufacture of the prepreg, and based on the hypothesis that the state of the ear portion of the fiber sheet affects the occurrence of unintentional thickness variation in the prepreg. Prior to the manufacture of the prepreg, it is appropriately determined whether or not the prepreg is likely to cause an undesired thickness variation (whether it can be suitably used for the manufacture of the prepreg). In order to provide a method for inspecting fiber sheets, we have conducted intensive research. As a result, the present invention has been achieved.

That is, the fiber sheet inspection method of the present invention is a fiber sheet inspection method used for the production of a prepreg by impregnating varnish, wherein the fiber sheet is treated with a fraying inhibitor having a function of preventing fiber fraying. The section of the ear portion of the fiber sheet has a kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m. The quality of the fiber sheet is judged based on the time until the section settles after the section is left on the surface of the inspection liquid of 40 mN / m or less and the section is left on the surface of the inspection liquid. It is characterized by that.

  Accordingly, whether or not the fiber sheet can be suitably used for manufacturing a prepreg in which unintentional fraying of the fiber is effectively prevented and variation in unintentional thickness is effectively prevented. Can be judged appropriately. That is, when the time until the section settles is a value within a predetermined range, the fiber sheet is a non-defective product (preferably used for manufacturing a prepreg in which unintentional thickness variation is effectively prevented. If the time until the section settles is out of the predetermined range, the fiber sheet is a nonconforming product (unintentional thickness variation was effectively prevented). It can be determined that it cannot be suitably used for the production of a prepreg, or the fraying of fibers cannot be sufficiently prevented.

  In the present invention, the “time until the section settles” means that the entire surface of the section is included in the inspection liquid after the section is left on the surface of the inspection liquid to release the support state. This is the time it takes to complete.

≪Fiber sheet inspection method≫
Hereinafter, the fiber sheet inspection method of the present invention will be described in detail.

As described above, the method for inspecting a fiber sheet of the present invention is a method for inspecting a fiber sheet that is impregnated with a varnish and used for manufacturing a prepreg, and the fiber sheet has a function of preventing fraying of the fiber. The section of the ear part of the fiber sheet has a kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m. The quality of the fiber sheet is judged based on the time until the section settles after the section is placed on the surface of the inspection liquid after being left on the surface of the inspection liquid of 40 mN / m or less. Features.

The kinematic viscosity at 25 ° C. of the inspection liquid may be 10 mm ² / s or more and 1000 mm ² / s or less, preferably 30 mm ² / s or more and 800 mm ² / s or less, and preferably 70 mm ² / s or more and 600 mm ^2. / S or less is more preferable.

  This makes it easier to handle the inspection liquid, and more appropriately whether or not it can be suitably used for manufacturing the prepreg 100 in which the unintentional thickness variation is effectively prevented in a shorter time. Judgment can be made.

  In addition, kinematic viscosity can be calculated | required by the measurement according to JISZ8803: 2011, for example. For the measurement of kinematic viscosity, for example, a capillary viscometer, a falling ball viscometer, a rotational viscometer, or a vibration viscometer can be used, but a capillary viscometer is preferably used.

  The surface tension of the inspection liquid may be 15 mN / m or more and 40 mN / m or less, preferably 17 mN / m or more and 36 mN / m or less, and more preferably 20 mN / m or more and 33 mN / m or less. .

  This makes it easier to handle the inspection liquid, and more appropriately whether or not it can be suitably used for manufacturing the prepreg 100 in which the unintentional thickness variation is effectively prevented in a shorter time. Judgment can be made.

  In addition, in this specification, unless otherwise indicated, surface tension refers to the surface tension at 25 ° C. and can be suitably obtained by a dropping method.

  The boiling point (boiling point at 1 atm) of the inspection liquid is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 150 ° C. or higher.

  Thereby, the involuntary volatilization of the inspection liquid during the sedimentation time measurement can be more effectively prevented, and the inspection reliability can be further improved.

  The vapor pressure at 25 ° C. of the test liquid is preferably 50 hPa or less, more preferably 40 hPa or less, and further preferably 20 hPa or less.

  Thereby, the involuntary volatilization of the inspection liquid during the sedimentation time measurement can be more effectively prevented, and the inspection reliability can be further improved.

  Examples of the inspection liquid include silicone oils such as dimethyl silicone, methyl phenyl silicone, methyl hydrogen silicone, and cyclic dimethyl silicone, mixed liquids in which two or more of these are mixed, solutions in which solutes are dissolved in the liquids, and the like. However, the testing liquid is preferably silicone oil, and more preferably dimethyl silicone.

  Silicone oil (especially dimethyl silicone) is excellent in chemical stability, and can be easily and stably obtained with stable various conditions such as boiling point and vapor pressure, resulting in superior inspection reliability. Can be. Moreover, what satisfy | fills the above preferable conditions about a boiling point, vapor pressure, etc. can be obtained easily.

  When dimethyl silicone is used as the test liquid, the weight average molecular weight of the dimethyl silicone is preferably 6000 or more and 10,000 or less, and more preferably 7000 or more and 9000 or less.

  Such dimethyl silicone satisfies the above-mentioned suitable conditions such as kinematic viscosity and surface tension, and can be obtained more easily and more stably.

  The temperature of the liquid for inspection at the time of inspection is preferably 10 ° C. or higher and 35 ° C. or lower, more preferably 15 ° C. or higher and 30 ° C. or lower, and further preferably 18 ° C. or higher and 28 ° C. or lower.

  Thereby, the conditions of the test liquid such as kinematic viscosity and surface tension at the time of measurement can be more preferably approximated as described above, and the test reliability can be further improved.

  The time when the fiber sheet 10 is judged to be non-defective (time until the section settles) is not particularly limited, but is preferably 20 seconds or more and 37 seconds or less, and is 22 seconds or more and 35 seconds or less. Is more preferable.

  Thereby, the accuracy of the inspection can be further improved while the time required for the inspection is relatively short.

  Although the thickness of the fiber sheet 10 is not specifically limited, It is preferable that they are 50 micrometers or more and 1000 micrometers or less, and it is more preferable that they are 80 micrometers or more and 500 micrometers or less.

  Thereby, the mechanical strength of the prepreg 100, the ease of handling, etc. can be made more excellent. Moreover, in the fiber sheet 10 having such a thickness, the influence of the condition of the ear portion 2 on the entire fiber sheet 10 and the entire prepreg 100 is large. Therefore, the effect by this invention is exhibited more notably when the thickness of the fiber sheet 10 is a value within the above range.

  The diameter of the fiber 1 constituting the fiber sheet 10 is preferably 2 μm or more and 40 μm or less, and more preferably 4 μm or more and 20 μm or less.

  Thereby, the mechanical strength of the prepreg 100, the ease of handling, etc. can be made more excellent, and the surface smoothness of the prepreg 100 is more excellent (the occurrence of unintentional irregularities is more effective. Can be suppressed). In addition, when the diameter of the fiber 1 is a value within the above range, the amount of air bubbles varies greatly depending on the formation conditions of the ear portion 2, and it has been particularly difficult to predict the quality of the fiber sheet 10 in the past. there were. On the other hand, in this invention, even if the diameter of a fiber is a value within the said range, the quality of a fiber sheet can be judged appropriately. That is, the effect of the present invention is more prominent when the fiber diameter is a value within the above range.

  The fiber sheet main body constituting the fiber sheet 10 is not particularly limited as long as it includes the fiber 1 and forms a sheet shape as a whole. For example, various nonwoven fabrics, various woven fabrics, paper, and the like can be used. A cloth is preferred.

  Thereby, the mechanical strength of the prepreg 100, the ease of handling, etc. can be made more excellent. Moreover, when the fiber sheet main body which comprises the fiber sheet 10 is a glass cloth, the influence of the conditions of the ear | edge part 2 on the fiber sheet 10 whole and the prepreg 100 whole is large. Therefore, the effect by this invention is exhibited more notably when the fiber sheet main body which comprises a fiber sheet is a glass cloth especially.

  The fraying preventive agent 21 constituting the ear part 2 may be made of any material as long as it has a function of preventing fraying of the fibers 1. Of the urethane resin and acrylic resin, It is preferable that at least one of these is included.

  Thereby, fraying of the fiber 1 can be more effectively prevented while sufficiently securing the ease of deformation of the fiber sheet 10.

  The fiber sheet 10 may be wound in a roll shape, for example. In such a case, the ear | edge part 2 is selectively provided in the both edges of the width direction of the fiber sheet 10, for example, and the ear | edge part 2 does not need to be provided in the both edges of a longitudinal direction. .

Area of the section used for testing (sections of the ear portion 2) is preferably at 1 mm ² or more 200000 mm ² or less, more preferably at 5 mm ² or more 50,000 mm ² or less, that is 10 mm ² or more 2000 mm ² or less Further preferred.

  Thereby, it is possible to improve the reliability of the inspection while preventing an increase in the size of the container used for the inspection (container for the inspection liquid) or an increase in the amount of the inspection liquid used. . Further, since a plurality of sections can be cut out from the single fiber sheet 10 and these can be suitably inspected, it is advantageous from the viewpoint of further improving the reliability of the inspection.

≪Prepreg≫
Next, the prepreg of the present invention will be described.

The prepreg of the present invention is a prepreg comprising a fiber sheet and a resin material impregnated in the fiber sheet, wherein the fiber sheet is treated with an anti-fraying agent having a function of preventing fiber fraying. A kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m to 25 mN / m. When standing on the surface of the test liquid, the time from the rest of the section to the surface of the test liquid until the section settles is 20 seconds or more and 37 seconds or less. And

  Thereby, it is possible to provide a prepreg in which fiber fraying hardly occurs and unintentional thickness variation is effectively prevented.

  Examples of the resin material 20 ′ constituting the prepreg 100 include epoxy resins, phenol resins, cyanate resins, maleimide resins, melamine resins, urethane resins, polyester resins, polyimide resins, polybutadiene resins, urea resins, and the like. It is preferable to include one or more selected from the group consisting of resins, phenol resins, cyanate resins, maleimide resins, melamine resins and urethane resins.

  Thereby, the dimension stability of the molded object manufactured using the prepreg 100 (for example, laminated body 1000 mentioned later), insulation, heat resistance, etc. can be made more excellent.

  The content of the resin material 20 ′ in the prepreg 100 is not particularly limited, but is preferably 5% by mass or more and 70% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

  Thereby, while being able to make the prepreg 100 easy to handle and moldability, the moldability of a molded body (for example, a laminate 1000 described later) manufactured using the prepreg 100 is further improved. It can be excellent.

≪Prepreg manufacturing method≫
Next, the manufacturing method of the prepreg of this invention is demonstrated.

  FIG. 3 is a longitudinal sectional view schematically showing a preferred embodiment of the method for producing a prepreg of the present invention, and FIG. 4 is a schematic diagram showing a configuration of a prepreg production apparatus that can be suitably used for producing the prepreg of the present invention. It is a longitudinal cross-sectional view shown in FIG.

As shown in FIG. 3, the method for manufacturing the prepreg 100 according to the present embodiment is a fiber that prepares a fiber sheet 10 including an ear portion 2 that has been treated with a fraying inhibitor 21 having a function of preventing fraying of the fiber 1. Sheet preparation step (1a), impregnation step (1b) for impregnating fiber sheet 10 with varnish 20 '' containing a resin material, and semi-curing step (1) for semi-curing the resin material to form semi-cured product 20 ' 1c). And as the fiber sheet 10, what satisfies the following conditions is used. That is, the section of the ear portion 2 of the fiber sheet 10 is made of an inspection liquid having a kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m to 30 mN / m. In the case where the sample is allowed to stand on the surface, the time from when the slice is left on the surface of the test liquid to when the slice is settled is 20 seconds or longer and 37 seconds or shorter.

  Accordingly, it is possible to provide a method for producing a prepreg that can efficiently produce a prepreg in which fiber fraying hardly occurs and unintentional thickness variation is effectively prevented.

<Fiber sheet preparation process>
In the fiber sheet preparation step, the fiber sheet 10 as described above is prepared.

  In this process, the fiber sheet 10 in which the ear | edge part 2 was formed previously may be prepared, or the fiber sheet main body without the ear | edge part 2 is prepared, and an ear | edge is prepared with respect to the said fiber sheet main body at this process. The part 2 may be formed.

  The ear | edge part 2 can be formed by providing the composition containing the fraying prevention agent (ear treatment agent) 21 with methods, such as a coating method, with respect to a fiber sheet main body, for example.

<Impregnation step>
In the impregnation step, the fiber sheet 10 is impregnated with a varnish 20 ″ containing a resin material.

  This step can be performed, for example, by immersing the fiber sheet 10 in the varnish 20 ″ or applying the varnish 20 ″ to the fiber sheet 10.

  The varnish 20 ″ may include a component (other component) other than the resin material. Examples of such components include a solvent, a plasticizer, an antioxidant, and an antifoaming agent.

Examples of the solvent constituting the varnish 20 '' include water; alcohols such as methanol and ethanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone;
Aliphatic hydrocarbons such as hexane; aromatics such as benzene and toluene; dimethylformamide; dimethyl sulfoxide, and the like. These can be used alone or in combination of two or more. , Preferably at least one selected from the group consisting of acetone, methyl ethyl ketone and dimethylformamide.

  As a result, the solvent can be efficiently removed in the manufacturing process of the prepreg 100 while the dissolved state of the resin material is good, and the productivity of the prepreg 100 can be further improved, and finally Thus, it is possible to more effectively prevent the solvent from remaining unintentionally in the prepreg 100 obtained and the occurrence of adverse effects due to the solvent.

  This step may be performed in a state where at least one of the fiber sheet 10 and the varnish 20 ″ is heated and heated. Thereby, the permeability of the varnish 20 ″ into the gaps of the fibers 1 constituting the fiber sheet 10 is improved, and the productivity and reliability of the prepreg 100 can be further improved.

  The treatment temperature in this step is not particularly limited, but is preferably 10 ° C. or higher and 80 ° C. or lower, and more preferably 15 ° C. or higher and 70 ° C. or lower.

<Semi-curing process>
In the semi-curing step, the resin material contained in the varnish 20 ″ applied to the fiber sheet 10 is semi-cured to obtain a semi-cured resin material 20 ′ (B stage resin).

  Thereby, the unintentional loss of the constituent material is effectively prevented, and the prepreg 100 with improved shape stability is obtained.

  Examples of the method for semi-curing the resin material include irradiation with energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and heating, but a simple apparatus can be used. Heating is preferable in that it is easy to adjust the polymerization degree (curing degree) of 20 ′. When this step is performed by heating, when the varnish 20 ″ includes a solvent, the polymerization reaction can be advanced and the solvent can be efficiently removed.

  When this step is performed by heating, the heating temperature (treatment temperature) varies depending on the composition of the varnish 20 ″, etc., but is preferably 80 ° C. or higher and 220 ° C. or lower, more preferably 120 ° C. or higher and 200 ° C. or lower. preferable.

  Each process mentioned above may be performed continuously, for example. For example, as shown in FIG. 4, when the fiber sheet 10 is wound in a roll shape, the above-described steps can be preferably performed continuously.

  That is, the prepreg manufacturing apparatus S100 shown in FIG. 4 accommodates a feeding roller S1 that feeds the fiber sheet 10 wound in a roll shape and a varnish 20 ″, and the fiber sheet 10 that is fed by the feeding roller S1 is immersed therein. The prepreg 100 obtained by semi-curing the resin material contained in the immersion tank S2, the heating means (semi-curing means) S3 for heating the fiber sheet 10 provided with the varnish 20 '', and the varnish 20 ''. And using the prepreg manufacturing apparatus S100 having such a configuration, the above-described steps can be preferably performed continuously, and the productivity of the prepreg 100 is particularly improved. It can be excellent.

  Moreover, the prepreg 100 can be suitably stored by winding the manufactured prepreg 100 in a roll shape. In addition, the operability when other processing is performed on the prepreg 100 is also improved. Further, the prepreg 100 can be cut out and used by a necessary size (length) when necessary.

≪Laminated body≫
Next, the laminated body of this invention is demonstrated.
FIG. 5 is a longitudinal sectional view schematically showing a preferred embodiment of the laminate of the present invention.

  As shown in FIG. 5, in the laminate 1000, a plurality of the prepregs 100 of the present invention as described above are laminated, and the prepregs 100 are joined to each other by a cured product (resin material) 20 of the resin material 20 ′.

  Thereby, the reliable laminated body manufactured using the prepreg can be provided. In particular, the laminate can be suitably applied to various substrates.

  In the configuration shown in the figure, the laminate 1000 is a laminate of seven prepregs, but the number of laminates of the prepreg 100 is not particularly limited, but is preferably 3 or more and 30 or less, and preferably 4 or more and 20 sheets. The following is more preferable.

  Thereby, the mechanical strength, shape stability, and the like of the laminate can be further improved. Further, for example, it can be suitably applied to various substrates. Further, conventionally, as the number of prepregs laminated increases, problems such as warpage occur more significantly, and the problem that the reliability of the laminated body decreases more significantly, the present invention, As described above, even when the number of stacked layers is relatively large, it is possible to effectively prevent the occurrence of the above problems. That is, when the number of laminated prepregs 100 is a value within the above range, the effect of the present invention is more remarkably exhibited.

The prepreg 100 can be joined by, for example, heating and pressing.
The pressure applied when the prepreg 100 is joined is preferably 0.5 MPa or more and 50 MPa or less, and more preferably 1 MPa or more and 30 MPa or less.

  Thereby, the joining strength in the obtained laminated body 1000 and the reliability of the laminated body 1000 can be made more excellent, while preventing the enlargement of the apparatus used for joining of the prepreg 100 more effectively.

  The treatment temperature at the time of joining the prepreg 100 is preferably 100 ° C. or higher and 300 ° C. or lower, and more preferably 150 ° C. or higher and 250 ° C. or lower.

  Thereby, the bonding strength in the obtained laminated body 1000 and the reliability of the laminated body 1000 can be further improved, and it is advantageous from the viewpoint of energy saving and productivity of the prepreg 100.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to these, The deformation | transformation in the range which can achieve the objective of this invention, improvement, etc. are included in this invention. .

For example, the method for producing a prepreg of the present invention may have steps other than those described above.
Further, the prepreg of the present invention is not limited to those manufactured by the manufacturing method as described above, and may be manufactured by any method.

  Moreover, the prepreg of this invention is not limited to what was manufactured using the manufacturing apparatus mentioned above. Moreover, you may perform only the one part process of the manufacturing method of a prepreg using another apparatus.

  Hereinafter, the present invention will be described in detail based on specific experimental examples, examples, and comparative examples, but the present invention is not limited thereto. In addition, about the operation and process which do not show temperature conditions in particular, it performed at 25 degreeC.

[1] Preparation of fiber sheet (Experimental example A)
First, a glass cloth as a fiber sheet main body was prepared.
The glass cloth is composed of glass fibers of T glass, and the glass fiber has an average diameter of 9 μm, a density of 1.19 g / cm ³ , a thickness of 185 μm, a basis weight of 220 g / m ² , and a width. Was prepared under the condition of 100 cm and wound into a roll.

  Next, while feeding out the fiber sheet main body, to both edges in the width direction of the fiber sheet main body, a composition containing a urethane-based resin as a fray preventing agent is applied by a kiss roll method, and then subjected to heat treatment, respectively. An ear part having a width of 10 mm was formed to obtain a fiber sheet. The manufactured prepreg was wound up in a roll shape. The content of the ear treatment agent in the ear was determined by TG / DTA (thermogravimetric / differential thermal analysis) using a TG-DTA apparatus (EXSTAR 6000 TG / DTA 6200, manufactured by Seiko Instruments Inc.), 3.0 mass. %Met.

(Experimental examples B to H)
While adjusting the composition of the composition used for forming the ear part (the type and content of the anti-fraying agent (ear treatment agent) and the content of the solvent), the amount applied to the fiber sheet body is adjusted, and the ear part is adjusted. A fiber sheet was produced in the same manner as in Experimental Example 1 except that the conditions of (ear treatment agent) were as shown in Table 1.

[2] Inspection of Fiber Sheet The following inspection was performed on the fiber sheets manufactured in each of the above experimental examples.
First, a 7 mm square section was cut out from the ear portion of the fiber sheet of each experimental example.

The section obtained in this manner is allowed to stand on the surface of the test liquid made of dimethyl silicone having a weight average molecular weight of 8000, and after the section is left on the surface of the test liquid, the section is settled. Time was measured. The liquid for inspection had a kinematic viscosity at 25 ° C. of 100 mm ² / s, a surface tension of 20.0 mN / m, a boiling point (boiling point at 1 atm) of 150 ° C. or higher, and a vapor pressure at 25 ° C. of 20 hPa or lower. .

In addition, the kinematic viscosity of the liquid for inspection was calculated | required by the measurement according to JISZ8803: 2011 using the cone-plate type rotary viscometer (the Toki Sangyo company make, RE-215). The surface tension of the test liquid was determined by the hanging drop method using an automatic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.).
These results are shown in Table 1.

[3] Production of prepreg (Example 1)
A prepreg was produced as follows using the fiber sheet produced in Experimental Example A.
First, a prepreg manufacturing apparatus as shown in FIG. 4 was prepared, and a roll-shaped fiber sheet was attached to a feeding roller.

  Next, the fiber sheet fed from the feeding roller is immersed in the varnish accommodated in the dipping tank, and further, the resin material contained in the varnish given to the fiber sheet is subjected to heat treatment by a heating means and semi-cured. And the solvent was removed to obtain a prepreg.

  As the varnish, a composition containing an epoxy resin as a resin material (uncured resin material) and acetone as a solvent was used. The heat treatment by the heating means was 180 ° C. × 240 seconds. The manufactured prepreg was wound up by a winding roller. The content of the resin material (epoxy resin) in the prepreg was 57% by mass.

(Examples 2 to 6)
A prepreg was produced in the same manner as in Example 1 except that the fiber sheet produced in Experimental Examples BF was used instead of that produced in Experimental Example A.

(Comparative Examples 1 and 2)
A prepreg was produced in the same manner as in Example 1 except that the fiber sheet produced in Experimental Examples G and H was used instead of that produced in Experimental Example A.
The conditions of the prepregs of the respective examples and comparative examples are summarized in Table 1.

[4] Evaluation [4.1] Fraying of fibers The prepregs of Examples and Comparative Examples produced as described above were visually observed and evaluated according to the following criteria.

A: No fiber fraying is observed.
B: Fraying of the fiber is hardly recognized.
C: Slight fraying of fibers is observed.
D: Fiber fraying is clearly recognized.
E: Fiber fraying is noticeable.

[4.2] Variation in thickness The prepregs of each Example and Comparative Example manufactured as described above were cut out by a length of 100 cm to obtain a sheet of 100 cm × 100 cm.

  For the sheet, 10 points are extracted at random for each of the central 10 cm × 10 cm area (first area) and the area where the ears are provided (second area). The thickness of the prepreg was measured using a micrometer (manufactured by Mitutoyo Corporation).

  The average value T1 [μm] of the thickness in the first region and the average value T2 [μm] of the thickness in the second region were determined and evaluated according to the following criteria. It can be said that the smaller the value of T2-T1, the smaller the variation in the thickness of the prepreg. In each of the above Examples and Comparative Examples, the value of T2 was equal to or greater than the value of T1.

A: The value of T2-T1 is less than 10 μm.
B: The value of T2-T1 is 10 μm or more and less than 20 μm.
C: The value of T2-T1 is 20 μm or more and less than 35 μm.
D: The value of T2-T1 is 35 μm or more and less than 50 μm.
E: The value of T2-T1 is 50 μm or more.
These results are summarized in Table 2.

  As is apparent from Table 2, in the fiber sheet inspection method, various fiber sheets are preferably used for manufacturing a prepreg in which fiber fraying hardly occurs and unintentional thickness variation is effectively prevented. It was possible to judge appropriately whether or not it was possible. In all of the prepregs of the present invention, fraying of the fibers hardly occurred, and unintentional thickness variation was effectively prevented. On the other hand, in the comparative example, a satisfactory result was not obtained.

  For each of the examples and comparative examples, seven sheets obtained by cutting the prepreg obtained as described above into a size of 100 cm × 100 cm were superposed, and in this state, the pressure was 3 MPa and the temperature was 175 ° C. A heat and pressure treatment was performed to obtain a laminate in which a plurality of prepregs were joined. A test piece having a size of 10 cm × 1 cm was cut out from the vicinity of the center of the laminate, and the test piece was subjected to a 90 ° peel test to obtain a bonding strength (peel strength). As a result, in the present invention, the bonding strength was excellent, whereas in Comparative Example 1, sufficient bonding strength was not obtained.

Also, except for variously changed the area sections in the range of 1 mm ² or more 200000 mm ² or less, where the was produced and inspection of the fiber sheet of each experimental example and the fiber sheet in the same manner, the same results Obtained.

  In addition, as a varnish, instead of an epoxy resin, a prepreg was produced in the same manner as in each of the above Examples and Comparative Examples, except that a resin containing a phenol resin, a cyanate resin, a maleimide resin, a melamine resin, and a urethane resin was used. As a result of evaluation, the same result as described above was obtained.

  As the varnish, prepreg was produced and evaluated in the same manner as in each of the above Examples and Comparative Examples, except that each containing methyl ethyl ketone and methyl formamide was used instead of acetone. Obtained.

1000: Laminated body 100: Prepreg 10: Fiber sheet 1: Fiber 2: Ear part 21: Fray prevention agent (ear treatment agent)
20: Resin material (cured product)
20 ': Resin material (semi-cured product)
20 ″: Varnish S100: Prepreg manufacturing apparatus S1: Feeding roller S2: Dipping tank S3: Heating means (semi-curing means)
S4: Winding roller

Claims (12)

A method for inspecting a fiber sheet impregnated with a varnish and used for producing a prepreg,
The fiber sheet is provided with an ear that has been treated with a fray-preventing agent having a function of preventing fiber fraying,
The section of the ear part of the fiber sheet is placed on the surface of the test liquid having a kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m to 40 mN / m. A method for inspecting a fiber sheet, wherein the quality of the fiber sheet is determined based on a time from when the section is allowed to stand to rest on the surface of the inspection liquid until the section is settled.   2. The fiber sheet is judged to be a non-defective product when the time from when the section is allowed to stand on the surface of the test liquid to when the section settles is 20 seconds or more and 37 seconds or less. 2. A method for inspecting a fiber sheet according to 1. Area of the sections, the fiber sheet inspection method according to claim 1 or 2 is 1 mm ² or more 200000 mm ² or less. A prepreg comprising a fiber sheet and a resin material impregnated in the fiber sheet,
The fiber sheet is provided with an ear that has been treated with a fray-preventing agent having a function of preventing fiber fraying,
The section of the ear part of the fiber sheet is placed on the surface of the test liquid having a kinematic viscosity at 25 ° C. of 10 mm ² / s to 1000 mm ² / s and a surface tension of 15 mN / m to 25 mN / m. A prepreg characterized by having a time from 20 seconds to 37 seconds after the section is left standing on the surface of the test liquid when it is left standing.   The prepreg according to claim 4, wherein the fiber sheet main body constituting the fiber sheet is a glass cloth.   The prepreg according to claim 4 or 5, wherein the fraying inhibitor contains at least one of a urethane resin and an acrylic resin.   The prepreg according to any one of claims 4 to 6, wherein the test liquid is dimethyl silicone.   The prepreg according to claim 7, wherein the dimethyl silicone has a weight average molecular weight of 6000 or more and 10,000 or less.   The said resin material contains 1 type, or 2 or more types selected from the group which consists of an epoxy resin, a phenol resin, cyanate resin, a maleimide resin, a melamine resin, and a urethane resin. Prepreg. A fiber sheet preparation step of preparing a fiber sheet including an ear portion treated with a fraying inhibitor having a function of preventing fiber fraying; and
An impregnation step of impregnating the fiber sheet with a varnish containing a resin material;
A semi-curing step of semi-curing the resin material,
As the fiber sheet, the surface of the liquid for inspection having a kinematic viscosity at 25 ° C. of 10 mm ² / s or more and 1000 mm ² / s or less and a surface tension of 15 mN / m or more and 30 mN / m or less as the fiber sheet. When the prepreg is allowed to stand, a prepreg having a time from 20 seconds to 37 seconds after the section is allowed to settle on the surface of the test liquid is used. Method.   The method for producing a prepreg according to claim 10, wherein the varnish contains at least one selected from the group consisting of acetone, methyl ethyl ketone, and dimethylformamide as a solvent.   A laminate comprising a plurality of the prepregs according to any one of claims 4 to 9, wherein the prepregs are bonded together by a cured product of the resin material.

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