JPWO2015076283A1 - Fiber reinforced thermoplastic resin sheet - Google Patents

Abstract

The fiber reinforced thermoplastic resin sheet of the present invention is a fiber reinforced thermoplastic resin sheet containing reinforced fibers and a thermoplastic resin, and is a fiber reinforced thermoplastic resin sheet whose breaking energy value satisfies a specific condition. It is a fiber-reinforced thermoplastic resin sheet having high resin impregnation property and breaking energy, and less physical property variation due to orientation. At this time, the mass ratio between the reinforcing fiber and the thermoplastic resin is preferably 85/15 to 40/60, and the reinforcing fiber is preferably glass fiber or carbon fiber.

Description

  The present invention relates to a fiber reinforced thermoplastic resin sheet. More specifically, the present invention relates to a fiber reinforced thermoplastic resin sheet that has a high degree of adhesion between a reinforced fiber and a thermoplastic resin, has few voids, and has a large energy absorption amount when the sheet breaks, and is suitable as a material for an impact absorbing member.

  In recent years, fiber reinforced thermoplastic resin sheets have been widely used as molding intermediates or molded articles. In particular, the molding intermediate is called a stampable sheet, and is cut into a predetermined shape, for example, heated to a temperature near or above the softening point or the melting point of a thermoplastic resin by far-infrared heating, etc. It is placed in a mold and pressed and cooled and solidified to form a final molded product.

  Such a molding intermediate is generally used as a thermoplastic resin powder, a film, or a reinforced fiber (eg, glass fiber, carbon fiber) mat (eg, chopped strand mat) or assorted product. The sheet is produced by melt impregnation at a temperature higher than at least the softening point or melting point of the thermoplastic resin.

  Examples of conventional methods for producing this molding intermediate include the following methods.

A. Press molding:
A mold having excellent fitting accuracy for attachment to the press and having a heating and cooling device is heated to a temperature higher than at least the softening point or melting point of the thermoplastic resin by a heating medium. A reinforcing fiber and a thermoplastic resin sheet or thermoplastic resin powder are placed in this mold and melt impregnated by heating and pressing. Next, the mold is cooled with a refrigerant, and the molten resin is pressurized and cooled and solidified to obtain a fiber-reinforced thermoplastic resin sheet.

B. Mold transfer cooling molding:
A die having excellent fitting accuracy attached to a pair of presses that can be heated and / or cooled is used. First, the mold is attached to one press and heated at least to a temperature higher than the softening point or melting point of the thermoplastic resin, and then the reinforcing fiber and the thermoplastic resin sheet or thermoplastic resin powder are placed in the mold. And melt impregnation by heating and pressing. Next, the mold in which the reinforcing fibers and the molten resin are arranged is transferred to the other press, and the molten resin is pressurized and cooled and solidified to obtain a fiber-reinforced thermoplastic resin sheet.

C. Double belt press molding:
A device called a double belt press device having an endless belt and an auxiliary device for heating and / or cooling is used. The reinforcing fiber and the thermoplastic resin sheet or thermoplastic resin powder are placed in a double belt press machine, melt impregnated by heating and pressing, and continuously pressed and cooled and solidified to obtain a fiber-reinforced thermoplastic resin sheet. obtain.

D. Roll forming:
An apparatus having at least a pair of heating rolls and at least a pair of cooling rolls is used. The reinforcing fiber and the thermoplastic resin sheet or the thermoplastic resin powder are melted and impregnated by heating and pressurizing with a heating roll, and then pressurized and cooled and solidified with a cooling roll to obtain a fiber-reinforced thermoplastic resin sheet.

In the press molding of A and the mold conveyance cooling molding of B, it is possible to obtain a thermoplastic resin sheet having excellent physical properties with high adhesion between the reinforcing fiber and the thermoplastic resin and few voids. However, there is a drawback that the production efficiency is very bad. Further, although the production efficiency of the double belt press molding of C and the roll molding of D is very high, the adhesion between the reinforcing fiber and the thermoplastic resin is low, and there is a drawback that it is easy to obtain a product in which voids remain in some places. If voids remain, they tend to become the starting point of destruction, even if a small amount of deformation occurs, peeling damage occurs, the physical property variation becomes large, and there is a problem that it is difficult to use for materials that require energy absorption performance such as shock absorbing members .
As described above, each method has advantages and disadvantages, and a thermoplastic resin sheet having high efficiency, high adhesion between the reinforcing fiber and the thermoplastic resin, and few voids has not been obtained.

  In view of this situation, after reinforcing fibers are pre-opened and pre-impregnated with a thermoplastic resin, tapes cut to any length are laminated in a non-direction (random), covered with a heat-resistant release sheet, and thermoplastic A press molding method using a heat-resistant release sheet has been proposed in which air is sufficiently discharged by a press machine heated to a temperature higher than the softening point or melting point of the resin, and then conveyed to a cooling mold and subjected to a cooling press. Yes. For example, Patent Documents 1 and 2 propose materials having good fluidity and resin impregnation properties, but none of them defines a suitable range as a material for an impact absorbing member.

Japanese Patent No. 2885038 Japanese Patent No. 2877052

  An object of the present invention is to provide a fiber-reinforced thermoplastic resin sheet having high resin impregnation property and breaking energy, and having little property variation due to orientation.

  As a result of intensive studies, the present inventors can provide a fiber-reinforced thermoplastic resin sheet having high resin impregnation property and breaking energy and less physical property variation due to directionality by using a sheet having the following configuration. We found out and came to the present invention. The fiber-reinforced thermoplastic resin sheet of the present invention is obtained by earnestly examining the conditions mainly based on a press method using a heat-resistant release sheet, but has not been studied in the prior art. The present invention provides a fiber reinforced thermoplastic resin sheet that is suitable as a material for an impact absorbing member, has no directionality, and has high impact absorbing performance and moldability.

That is, the fiber-reinforced thermoplastic resin sheet of the present invention has the following configuration.
[1] A fiber reinforced thermoplastic resin containing a reinforced fiber and a thermoplastic resin, wherein the value of breaking energy satisfies the following (1) and (2): Sheet.
_{(1) E 0, E 45} , and _{E 90} are both 4J more _{(2) E 0 / E A} , the range of E 45 / _{E A,} and _E 90 / _E both _A is 0.85 to 1.15 (Here, E ₀ , E ₄₅ , and E ₉₀ are the amount of rupture energy in the direction of 0 °, the amount of rupture energy in the direction of 45 °, respectively, when an arbitrary direction is set to 0 ° in the sheet surface, and a breaking energy amount in the direction of 90 °, _{E a is} the average value of _{E 0, E 45, E 90} .)
[2] The fiber reinforced thermoplastic resin sheet according to [1], wherein a mass ratio of the reinforced fiber and the thermoplastic resin (reinforced fiber / thermoplastic resin) is 85/15 to 40/60.
[3] The fiber-reinforced thermoplastic resin sheet according to [1] or [2], wherein the reinforcing fibers are glass fibers or carbon fibers.
[4] The fiber-reinforced thermoplastic resin sheet according to any one of [1] to [3], wherein the thermoplastic resin is a polyolefin resin or a polyamide resin.
[5] The fiber-reinforced thermoplastic resin sheet is thermocompression-bonded by randomly dispersing and laminating thin film pieces of tape each having a length of 5 mm to 100 mm, a width of 5 mm to 60 mm, and a thickness of 0.05 mm to 0.3 mm. The fiber-reinforced thermoplastic resin sheet according to any one of [1] to [4].
[6] JIS of a fiber reinforced thermoplastic resin sheet containing the reinforced fiber and a thermoplastic resin
The fiber-reinforced thermoplastic resin sheet according to any one of [1] to [5], wherein the value of deflection at break obtained by K 7017: 1999 is 3 mm or more.
[7] The fiber-reinforced thermoplastic resin sheet according to any one of [1] to [6], wherein a ratio of an air layer present in the fiber-reinforced thermoplastic resin sheet is 3% or less.

  According to the present invention, it is possible to provide a fiber-reinforced thermoplastic resin sheet having high resin impregnation property and breaking energy, and having little property variation due to orientation.

  Representative examples of the reinforcing fibers in the present invention include inorganic fibers such as carbon fibers, silicon carbide fibers and glass fibers, metal fibers such as boron fibers, and organic fibers such as aramid fibers. In view of cost and the elastic modulus and mechanical strength of the resulting molded article, inorganic fibers such as glass fibers and carbon fibers are preferred. These fibers are preferably used by drawing continuous fibers and opening them sufficiently.

  Representative examples of the thermoplastic resin include polyamide resins such as polyamide 6, polyamide 12, polyamide 66, polyamide 46, polymetaxylylene adipamide (MXD6), polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyethylene, Examples thereof include polyolefin resins such as polypropylene, polyether ketone resins, polyphenylene sulfide resins, polyether imide resins, and polycarbonate resins.

Typical examples of particularly preferred thermoplastic resins are as follows. These can be used as appropriate depending on the use (or desired properties) of the molded article.
(1) Polyolefin resins are preferred when low cost, fluidity during molding, water resistance, hot water resistance, or chemical resistance is required. Polypropylene is particularly preferable because it is easily available. In the present invention, it is preferable to use acid-modified polypropylene. This is because it is particularly excellent in adhesiveness with the reinforcing fiber described later.
(2) When abrasion resistance, oil resistance, or long-term heat resistance is required, polyamide-based resins are preferable, and polyamide 6, polyamide 66, and MXD6 resin are particularly preferable.

The fiber-reinforced thermoplastic resin sheet of the present invention has a value of breaking energy (E ₀ , E ₄₅ , and E ₉₀ ) of 4 J or more. The amount of energy to break is determined according to JIS K 7017: 1999 “Fiber-Reinforced Plastics—How to Obtain Bending Properties” and the bending property test of the three-point bending method (Method A) using an autograph AG-X 50 kN manufactured by Shimadzu Corporation. The energy (J) at break obtained by TRAPEZIUM2 (software). When the amount of breaking energy is less than 4 J, even if a small amount of deformation occurs, the detachment failure of the reinforcing fibers is likely to occur and the variation in physical properties increases, which is not preferable. A more preferable range is 5 J or more, and a further preferable range is 6 J or more. The upper limit of the value of the breaking energy amount is not particularly set, but is about 30 J considering the raw materials to be used.
In addition, the test piece is set to 0 ° in any direction in the sheet, and the test piece whose thickness is the span length (thickness is 4 mm, width is 25 mm, span length is 64 mm), and the test is 45 ° from this direction. A piece and a 90 ° test piece are each cut out from the sheet at n = 10, and the amount of breaking energy is measured.
_Further, in the range of _{E 0 / E A, E 45} / E A, and any _E 90 / _{E A} is 0.85 to 1.15. By being in this range, a fiber-reinforced thermoplastic resin sheet with little variation in physical properties due to directionality can be obtained. _{E 0 / E A, E 45} / E A, and _E 90 / _{E A} is preferably either in the range of 0.9 to 1.1.

The thickness of the fiber-reinforced thermoplastic resin sheet of the present invention is preferably 1.5 to 8 mm.
In addition, the fiber reinforced thermoplastic resin sheet is manufactured by dispersing and laminating thin film pieces of tape having a length of 5 mm to 100 mm, a width of 5 mm to 60 mm, and a thickness of 0.05 mm to 0.3 mm, and thermocompression bonding. Is desirable. The reinforcing fiber is untwisted, sufficiently spread, then impregnated with resin, cooled with a shaping roller, and then cut into an arbitrary length. Producing a tape in this way is effective in reducing the proportion of the air layer present in the fiber-reinforced thermoplastic resin sheet.
When the length of the tape is less than 5 mm, it is difficult to obtain high physical properties. On the other hand, when the length exceeds 100 mm, the molding fluidity is deteriorated and at the same time, the directionality is easily generated in the sheet, which is not preferable. A more preferable range is 10 to 50 mm, and a still more preferable range is 15 to 40 mm.

  Moreover, when the width of the tape is less than 5 mm, the opened state becomes insufficient, and voids are likely to remain, which is not preferable. Conversely, when the tape width exceeds 60 mm, it is not preferable because tape breakage is likely to occur in the production process and voids are likely to remain in the sheet forming process. A more preferable range is 10 to 45 mm, and a further preferable range is 15 to 40 mm. Note that it is preferable that the width of the tape and the length of the reinforcing fiber (tape length) be as close as possible because the directionality of the sheet is less likely to occur.

  When the thickness of the tape is less than 0.05 mm, the amount of reinforcing fibers is small and the production efficiency is deteriorated. Conversely, when the thickness of the tape exceeds 0.3 mm, the amount of reinforcing fibers is large, and the impregnation property of the resin is deteriorated. A more preferable range is 0.07 to 0.2 mm, and a still more preferable range is 0.09 to 0.15 mm.

  In the fiber reinforced thermoplastic resin sheet of the present invention, the mass ratio of the reinforced fiber and the thermoplastic resin (reinforced fiber / thermoplastic resin) is preferably 85/15 to 40/60. When the amount of reinforcing fibers exceeds 85% by mass, the amount of resin is small and voids are likely to remain, which is not preferable. Conversely, if it is less than 40% by mass, the physical properties of the sheet are lowered, which is not preferable. A more preferable range of the amount of reinforcing fibers is 45 to 75% by mass, a further preferable range is 50 to 70% by mass, a more preferable range of the thermoplastic resin is 25 to 55% by mass, and a further preferable range is 30 to 30% by mass. 50% by mass. The tape is also preferably produced with this mass ratio.

  Further, it is desirable that the value of the deflection at break obtained by JIS K 7017: 1999 “Fiber-reinforced plastics—How to obtain bending characteristics” / three-point bending method (A method) is 3 mm or more. If it is less than 3 mm, the amount of deformation until breakage is insufficient, and a sufficient energy absorption effect cannot be obtained. Although it is desirable that the amount of deformation is large, it is appropriately designed in consideration of the elastic modulus depending on the type and amount of reinforcing fibers. A more preferable deformation amount is 3.4 to 6 mm, and a further preferable deformation amount is 3.8 to 5.5 mm.

  Moreover, it is preferable that the ratio of the air layer which exists in a fiber reinforced thermoplastic resin sheet is 3% or less. If it exceeds 3%, peeling failure due to deformation tends to occur, the physical property variation becomes large, and the energy absorption effect is insufficient, which is not preferable. A more preferable range is 2% or less, and a further preferable range is 1% or less. The ratio of the air layer in the present invention (void amount) is determined by embedding the central part and peripheral part of the sheet with epoxy resin, polishing the cross section, finishing to a mirror surface, taking an enlarged photograph of the cross section, and determining the void generation area. It is a ratio (%) obtained by measuring and obtaining the average value.

  In addition, the thermoplastic resin may contain additives such as a thermal degradation inhibitor, an oxidation degradation inhibitor, and an ultraviolet absorber as necessary. The content of these additives may vary depending on the purpose, but usually these additives are preferably 0.5% by mass or less, more preferably 0.2 to 0.5% by mass, respectively. It is added within the range.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, the measurement of each physical property is as follows.

Breaking energy amount:
JIS K 7017: 1999 “Fiber-reinforced plastics—How to obtain bending properties” A bending property test was performed according to the three-point bending method (A method). Using an autograph AG-X 50 kN manufactured by Shimadzu Corporation, the energy (J) at break was determined by TRAPEZIUM2 (software). The test piece is set to 0 ° in any direction in the sheet, and the test piece whose direction is the span length (thickness is 4 mm, width is 25 mm, span length is 64 mm), test piece at 45 ° from this direction, A 90 ° test piece was cut out from the sheet at n = 10, and E ₀ , E ₄₅ , and E ₉₀ (each average value of n = 10) were obtained. The average value of the three-way _{(E A)} was also determined.
Deflection at break:
JIS K 7017: 1999 “Fiber-reinforced plastics—How to obtain bending properties”, according to the three-point bending method (A method). As the test piece, the 0 ° test piece was used.
Air layer ratio (void amount):
The amount of voids in the fiber reinforced thermoplastic resin sheet was measured by embedding the center and periphery of the sheet with epoxy resin, polishing the cross section, finishing it into a mirror surface, taking an enlarged photograph of the cross section, and measuring the void generation area. The average value was obtained.

(Example 1)
  As the reinforcing fiber, continuous glass fiber (manufactured by Nippon Electric Glass Co., Ltd., ER2310-431N, 2310Tex, 4000f) is unwound so as not to twist while rotating two rovings, and is opened through a roller with a diameter of 2 cm. Thereafter, the resin was continuously impregnated through a 240 ° C. resin bath containing acid-modified polypropylene (manufactured by Prime Polymer Co., Ltd., blend of J139 and MMP006, melting point 160 ° C.) having a pressure of 0.6 MPa. Then, after crushing with a shaping roller and solidifying by cooling, cutting is performed, and 75 parts by mass of glass fiber is impregnated with 25 parts by mass of polypropylene resin acid-modified, width 30 mm, length 35 mm, thickness 0.1 mm A tape was prepared. Then, after laminating in an aluminum heat-resistant release container in a non-directional direction, the air was sufficiently removed in a heating mold heated to 240 ° C., then pressed in a cooling mold at 100 ° C., and 4 mm A thick sheet was produced.
  The ratio of the air layer of the obtained sheet was 0.4%, and the average value of the breaking energy was 6.1 J (E ₀: 6.2J, E₄₅: 6.0J, E₉₀: 6.1J), and the deflection at break was 3.6 mm.

(Example 2)
  Using 40 parts by mass of general-purpose polyamide 6 (Toyobo Co., Ltd., RV2.7) as a thermoplastic resin in 60 parts by mass of glass fiber as a reinforcing fiber, the same method as in Example 1, width 40 mm, length 35 mm, thickness 0 A 1 mm tape was produced. Then, after laminating in a heat-resistant mold release container made of aluminum in a non-directional direction, after sufficiently removing air in a heating mold heated to 260 ° C., pressing in a cooling mold at 140 ° C. and 4 mm A thick sheet was produced.
  The ratio of the air layer of the obtained sheet was 0.3%, and the average value of the breaking energy was 8.2 J (E ₀: 8.2J, E₄₅: 8.1J, E₉₀: 8.3 J), and the deflection at break was 3.9 mm.

Example 3
  Polypropylene that was acid-modified to 53 parts by mass of carbon fiber in the same manner as in Example 1 except that four continuous carbon fiber rovings (IMS40, 340Tex, 6000 filaments manufactured by Toho Tenax Co., Ltd.) were used as the reinforcing fibers in the horizontal unraveling. A strip-shaped tape having a width of 15 mm, a length of 20 mm, and a thickness of 0.12 mm, which was impregnated with 47 parts by mass of resin, was produced. Thereafter, in the same manner as in Example 1, the thermoplastic resin in the tape was heated to 240 ° C. through a heat-resistant release container made of aluminum, and then a fiber-reinforced thermoplastic resin sheet having a thickness of 4 mm was produced with a cooling press at 100 ° C. did.
  The ratio of the air layer of the obtained sheet was 0.8%, and the average value of the amount of breaking energy was 9.0 J (E ₀: 8.9J, E₄₅: 8.9J, E₉₀: 9.1 J), and the deflection at break was 3.1 mm.

Example 4
The same method as in Example 2 except that four continuous carbon fiber rovings (IMS40, 340Tex, 6000 filaments manufactured by Toho Tenax Co., Ltd.) were used as reinforcing fibers in the same manner as in Example 2, and 52 parts by mass of polyamide resin in 48 parts by mass of carbon fiber. A strip-shaped tape having a width of 15 mm, a length of 20 mm, and a thickness of 0.1 mm was prepared. Thereafter, in the same manner as in Example 2, the thermoplastic resin in the tape was heated to 260 ° C. through an aluminum heat-resistant release container, and a 4 mm thick fiber-reinforced thermoplastic resin sheet was produced with a 140 ° C. cooling press. did.
The ratio of the air layer of the obtained sheet was 0.7%, the average value of the breaking energy was 12.3J (E ₀ : 12.3J, E ₄₅ : 12.2J, E ₉₀ : 12.4J), at break The deflection was 3.3 mm.

(Comparative Example 1)
  As a reinforcing fiber, a continuous glass fiber (manufactured by Nippon Electric Glass Co., Ltd., ER2310-431N, 2310Tex, 4000f) is used in the same manner as in Example 1 with the untwisted state remaining in the same manner as in Example 1. Cutting through the modified polypropylene resin layer without passing through the shaping roller, 75 parts by mass of glass fiber impregnated with 25 parts by mass of acid-modified polypropylene resin, width 4 mm, length 35 mm, thickness 0 A 32 mm tape was produced. Then, after laminating in an aluminum heat-resistant release container in a non-directional direction, heating and cooling presses were performed in the same manner as in Example 1 to produce a 4 mm thick sheet.
  The ratio of the air layer of the obtained sheet was 3.4%, and the average value of the breaking energy was 3.4 J (E ₀: 3.3J, E₄₅: 3.2J, E₉₀: 3.6J), and the deflection at break was 2.4 mm.

(Comparative Example 2)
  As a reinforcing fiber, a continuous glass fiber (manufactured by Nippon Electric Glass Co., Ltd., ER2310-431N, 2310Tex, 4000f) is used, and a polyamide-based sizing agent is dipped so that the fiber does not come apart. After cutting, together with the polyamide 6 powder (60 parts by mass of glass fiber, 40 parts by mass of polyamide) and non-directional lamination in a heat-resistant release container made of aluminum, a sheet 4 mm thick by the same method as in Example 2 Was made.
  The ratio of the air layer of the obtained sheet was 3.6%, and the average value of the breaking energy was 3.7 J (E ₀: 3.9J, E₄₅: 3.6J, E₉₀: 3.7J), and the deflection at break was 2.8 mm.

  According to the present invention, a fiber-reinforced thermoplastic resin sheet having a high resin impregnation property and breaking energy and less physical property variation due to orientation can be obtained.

Claims (7)

A fiber-reinforced thermoplastic resin sheet containing reinforcing fibers and a thermoplastic resin, wherein the value of the amount of breaking energy satisfies the following (1) and (2).
_{(1) E 0, E 45} , and _{E 90} are both 4J more _{(2) E 0 / E A} , the range of E 45 / _{E A,} and _E 90 / _E both _A is 0.85 to 1.15 (Here, E ₀ , E ₄₅ , and E ₉₀ are the amount of rupture energy in the direction of 0 °, the amount of rupture energy in the direction of 45 °, respectively, when an arbitrary direction is set to 0 ° in the sheet surface, and a breaking energy amount in the direction of 90 °, _{E a is} the average value of _{E 0, E 45, E 90} .)   2. The fiber-reinforced thermoplastic resin sheet according to claim 1, wherein a mass ratio of the reinforcing fiber to the thermoplastic resin (reinforcing fiber / thermoplastic resin) is 85/15 to 40/60.   The fiber-reinforced thermoplastic resin sheet according to claim 1 or 2, wherein the reinforcing fibers are glass fibers or carbon fibers.   The fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 3, wherein the thermoplastic resin is a polyolefin resin or a polyamide resin.   The fiber reinforced thermoplastic resin sheet is characterized in that a thin film piece tape having a length of 5 mm to 100 mm, a width of 5 mm to 60 mm, and a thickness of 0.05 mm to 0.3 mm is randomly dispersed and laminated and thermocompression-bonded. The fiber-reinforced thermoplastic resin sheet according to any one of claims 1 to 4.   6. The value of the deflection at the time of the fracture | rupture calculated | required by JISK7017: 1999 of the fiber reinforced thermoplastic resin sheet containing the said reinforced fiber and a thermoplastic resin is 3 mm or more, A fiber-reinforced thermoplastic resin sheet according to claim 1.   The fiber reinforced thermoplastic resin sheet according to any one of claims 1 to 6, wherein a ratio of an air layer present in the fiber reinforced thermoplastic resin sheet is 3% or less.