JP2603520B2 - Method for producing glass fiber bundle and fiber reinforced resin body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a glass fiber bundle suitably used for producing a fiber reinforced resin body (FRP) and a method for producing FRP.

[Prior art] A sizing agent is added to glass fiber drawn from a bushing,
Glass fiber bundles (strands) that are bundled and dried are FRP
Widely used in the manufacture of

The components of the sizing agent are selected according to the purpose of use of the strand, but a sizing agent using an epoxy resin as a film-forming agent has been awarded for obtaining a high-strength FRP strand.

FRP requiring high strength is manufactured by using a long strand as a reinforcing fiber, impregnating this strand with a liquid thermosetting resin, and curing the resin in a state where the strand is tensioned. .

As a method for producing such a high-strength FRP, a drawing method and a filament winding method (FW method) are known.

[Problems to be Solved by the Invention] The performance required for high-strength FRP is gradually becoming severe recently, and a product having a large strength and a small decrease in strength after a boiling test or when subjected to repeated stress is desired. Have been.

The strength increases as the content of the reinforcing fibers in the FRP increases, but when the content of the reinforcing fibers increases, the impregnation of the liquid thermosetting resin tends to be uneven.

In addition, the strength of the FRP can be improved by using special fibers such as carbon fibers and aramid fibers, which have high strength as the reinforcing fibers.
It is more expensive than glass fiber commonly used for FRP, and there is a drawback in that the use is restricted from the viewpoint of price.

The present invention uses a glass fiber bundle (strand) having high strength and a small FRP with a small decrease in strength after a boiling test or when subjected to repeated stress, and a strand. An object of the present invention is to provide a method for obtaining an FRP with a small decrease in strength when a repeated stress is applied.

[Means for Solving the Problems] To achieve the above object, in the present invention, FRP
A glass fiber containing a sizing agent containing an epoxy resin as a reinforcing fiber is a long glass fiber bundle obtained by bundling and drying, and contained in a solution obtained by refluxing and extracting 20 gr of a glass fiber bundle for 1 hour using 25 ml of dioxane. The epoxy equivalent of the epoxy compound is not more than 600, and preferably the glass fiber bundle whose solid content of the solution is 0.02 to 0.5 gr, more preferably satisfying the above conditions, and the glass fiber bundle 50 gr When the absorbance of the epoxy group near 916 cm ^-1 and the absorbance of the aromatic adjacent 2H near 820 cm ^{-1 in} the infrared absorption spectrum of the solution extracted by ultrasonic washing with 300 ml of chloroform for 2 hours are A and B, respectively. A / B is a glass fiber having 0.2 or more, and a sizing agent containing an epoxy resin is added to the glass fiber bundle, the bundle is a long glass fiber bundle obtained by drying, and the glass fiber bundle 20 gr is mixed with 25 ml of dioxane. 1 using The epoxy equivalent of the epoxy resin contained in the solution extracted under reflux for
A long glass fiber bundle having a solid content of not more than 600, and preferably having a solid content of 0.02 to 0.5 gr, is impregnated with a liquid thermosetting resin, and the glass fiber bundle is cured under tension. Producing a fiber reinforced resin body by
Alternatively or more preferably, the above-mentioned conditions are satisfied, and the glass fiber bundle 50 gr is subjected to ultrasonic washing with 300 ml of chloroform for 2 hours, and an infrared absorption spectrum of the extracted solution is 916 cm ^-1.
Absorbance of epoxy group around and aromatic neighbor 2 around 820 cm ^-1
A long glass fiber bundle with an A / B of 0.2 or more, where the absorbance of H is A and B, respectively, is impregnated with a liquid thermosetting resin, and the glass fiber bundle is cured in a tensioned state to cure the fiber. A reinforced resin body is manufactured.

 Next, the present invention will be described more specifically.

The present inventor further improved the tensile strength, shear strength, and other properties of a high-strength FRP obtained by using a strand using an epoxy resin as a sizing agent, and strength after a boiling test or when repeated stress was applied. The following findings were obtained as a result of repeated experiments in order to obtain FRP with a small decrease.

(1) The epoxy ring of the epoxy resin contained in the strand obtained by adding and bundling a sizing agent containing the epoxy resin as a film-forming agent (hereinafter referred to as a sizing agent) has a function of heating during heating and drying, or Ring opening is easy due to reaction with other components in the sizing agent.

(2) The amount of the epoxy ring remaining in the strand has a close relationship with the performance such as the strength of the FRP, and the performance such as the strength of the FRP tends to improve as the remaining amount of the epoxy ring increases.

(3) The present inventor further studied the relationship of the above (2) and found the following.

(1) A preferable result is obtained by determining the composition of the sizing agent and the drying conditions of the strands so that the epoxy equivalent of a solution obtained by refluxing 20 gr of a strand with 25 ml of dioxane for 1 hour (hereinafter referred to as an extract) is 600 or less. What you can get.

(2) Strands more suitable as high strength FRP strands by determining the composition of the sizing agent and the drying conditions of the strands so that the solid content contained in the dioxane extract is 0.02 to 0.5 gr. What you can get.

(3) further satisfy the above conditions, and the glass fiber bundles 50gr the absorbance of the epoxy group in the vicinity of 916 cm ^-1 in the infrared absorption spectrum of the solution which was extracted and washed 2 hours ultrasound using chloroform 300 ml 820 cm ^-1 More preferable results can be obtained by determining the composition of the sizing agent and the drying conditions of the strands so that A / B is 0.2 or more when the absorbances of adjacent aromatic adjacent 2H are A and B, respectively.

 The present invention is a new proposal based on the above findings.

 Next, the present invention will be described more specifically.

The strand according to claims 1, 2 and 3 (hereinafter referred to as the present strand) can be manufactured as follows.

Epoxy resins to be included in the sizing agent include:
Bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, phenol borak type epoxy resin, alicyclic epoxy resin and the like can be suitably used.

It is appropriate to use an epoxy resin having an epoxy equivalent of 150 to 600, preferably 190 to 500.

The content of the epoxy resin in the sizing agent is suitably from 0.1 to 10% by weight, preferably from 0.5 to 5% by weight as a solid component.

The sizing agent preferably contains a lubricant, a coupling agent, and the like in addition to the epoxy resin, and may further contain a film-forming agent other than the epoxy resin.

Suitable lubricants include higher fatty acid esters, polyethylene glycol, etc., suitable coupling agents include γ-aminopyrropropyltriethoxysilane, and the like. Suitable film-forming agents other than epoxy resins include polyester resins and polyurethane resins. It is.

The amount of the sizing agent added is 0.
Suitably, it is 1 to 5% by weight, preferably 0.2 to 2% by weight.

The sizing agent is applied to the glass fiber drawn out of the bushing, and then dried.

As described above, the epoxy equivalent in the dioxane extract is 600 or less, preferably 500 or less, and the solid content in the extract is preferably 0.02 to 0.5 gr, particularly preferably 0.05 to 0.5 g.
The glass fiber bundle 50 gr was ultrasonically washed with 300 ml of chloroform for 2 hours to extract the solution, and the infrared absorption spectrum
The drying conditions and the composition of the sizing agent are determined so that A / B is 0.2 or more when the absorbance of the epoxy group near 916 cm ^-1 and the absorbance of the aromatic adjacent 2H near 820 cm ^-1 are A and B, respectively.

 The method for measuring the absorbance is as follows.

In the drawing [a graph showing an infrared absorption spectrum with the wave number (cm ⁻¹ ) on the horizontal axis and the transmittance on the vertical axis], it is indicated by A ′.
The absorbance A of the epoxy group peak near 916 cm ^-1 and the absorbance B of the aromatic adjacent 2H peak near 820 cm ^-1 indicated by B 'are determined from the graph. As a line m which is a reference when obtaining the absorbance A, a straight line connecting the valleys 1 and 2 (where the transmittance is high) near 980 cm ⁻¹ and 880 cm ⁻¹ is used.
880 cm ⁻¹ is used as a reference line n for obtaining B.
A straight line connecting the vicinity and valleys 2 and 3 near 780 cm ^-1 is adopted. The absorbances A and B are obtained as follows using the lengths a, b, c and d.

The extraction with dioxane is carried out by cutting 20 gr of the strand, preferably to about 2 to 3 cm, placing it in a flask, pouring 25 ml of dioxane, and boiling these extracts using a reflux condenser. Extraction time is 1
Set the time.

For extraction with chloroform, 50 gr of the strand is cut into preferably 2 to 3 cm, placed in a beaker, poured with 300 ml of chloroform, and the flask is immersed in a water tank equipped with a 40 kHz, 50 W ultrasonic transmitter to perform extraction. The extraction time is set to 2 hours.

At this time, it is appropriate to cover the upper part of the beaker with aluminum foil or the like to prevent evaporation and dissipation of chloroform.

Preferred conditions for obtaining a glass fiber bundle satisfying the above conditions are as follows, lowering the drying temperature described below,
The shorter the drying time and the smaller the content of a substance which easily reacts with the epoxy ring in the sizing agent, the more preferable results, that is, a glass fiber bundle that satisfies the conditions of claims 2 and 3 can be obtained. Can be.

(1) Perform drying at a low temperature and shorten the drying time.

To achieve the above object, it is important to increase the drying rate.

To this end, it is effective to keep the humidity of the drying atmosphere low, to forcefully circulate the atmosphere in the drying furnace, and to increase the contact area between the strand and the atmosphere.

In order to increase the contact area, when winding the strand into a cylindrical shape, it is preferable to reduce the size of the cylinder and to increase the porosity between the strands.

(2) Determine the composition of the sizing agent so that the epoxy ring does not open.

For this purpose, it is desirable to reduce the content of a substance which easily reacts with the epoxy ring, for example, a strong acid or an amine compound.

Next, a method for producing an FRP according to claims 4, 5, and 6 will be described.

Examples of the liquid thermosetting resin to be impregnated into the strand include an unsaturated polyester resin, an epoxy resin, a phenol resin and the like, and an epoxy resin is particularly preferable.

In the above resin, amine compounds, curing agents such as acid anhydrides, curing accelerators such as benzyldimethylamine, acid cal, talc, fillers such as titanium white,
A pigment or the like may be contained, and the thermosetting resin of the present invention includes a resin (resin composition) containing such an additive, and is generally referred to as a resin in the following description.

Resin is impregnated in an excessive amount into this strand according to a conventional method, and the excess resin is squeezed to make the amount of resin a predetermined amount, and heated while passing through a mold having a predetermined shape, or FW.
It is wrapped around a mold and heated. The resin is hardened under tension and the resin is hardened, and the strength is large, and the strength decreases little after a boiling test or when repeated stress is applied.
You can get P.

The weight% (GC) of this strand in FRP is 50 to 85 w
It is suitable that the content is t%, preferably 60 to 75 wt%.

[Operation] A strand obtained by subjecting a glass fiber bundle 20gr to reflux extraction with 25 ml of dioxane for 1 hour has an epoxy equivalent of 600 or less, and preferably has a solid content of 0.02 to 0.5gr. Preferably, the above conditions are satisfied, and 50 gr of the glass fiber bundle is mixed with 300 ml of chloroform.
When the absorbance of the epoxy group near 916 cm ^-1 and the absorbance of the aromatic adjacent 2H near 820 cm ^{-1 in} the infrared absorption spectrum of the solution extracted by ultrasonic cleaning for time are A and B, A / B is 0.2 or more. By using the strand as the reinforcing fiber for FRP, the bonding strength between the strand FRP and the matrix resin is increased, and the strength of the FRP is improved.

[Example 1] A sizing agent having the following composition was added to 23 µ glass fiber as a solid component in an amount of 0.5 wt%, and 4,000 were bundled to form strands.

Composition of sizing agent Emulsified epoxy resin (epoxy equivalent 190) 4.5wt% γ-aminopropyltriethoxysilane 0.5wt% higher fatty acid ester 0.6wt% acetic acid 0.2wt% 16kg of this strand is wound into a cylindrical shape, humidity 30% Was dried in a drying oven in which the atmosphere of the above was forcedly circulated.

 The drying time was 17 hours and the drying temperature was 120 ° C.

20 gr of this strand cut into 30 mm was placed in a flask, 25 ml of dioxane was added, and a reflux condenser was attached.
The dioxane was boiled and extracted for 1 hour.

The solid content in the extract is 0.06 gr, the epoxy equivalent is
330, also put 50 gr cut pieces of this strand 30 mm length into a flask, pour 300 ml of chloroform, and place the flask at 40K
916c of the infrared absorption spectrum of the solution which was immersed in a water tank equipped with an ultrasonic transmitter of 50 Hz and 50 W and subjected to ultrasonic extraction for 2 hours.
When the absorbance A of the epoxy group around m ^-1 and the absorbance of the aromatic adjacent 2H near 820 cm ^-1 are B, the ratio of the absorbances A and B is 0.25.
Met.

The strand was impregnated with a resin composition having the following composition, and a unidirectional reinforced sheet of 70 wt% GC was manufactured by the FW method.

Shear strength of this sheet was 7.56kg / mm ^2, also boiled 10
The strength retention after 0 hr was 92%.

Resin composition Epicoat 828 (trade name; manufactured by Yuka Shell) 100 parts by weight Amine-based curing agent 10 parts by weight [Example 2] Using the same sizing agent as in Example 1, using a strand dried at 120 ° C for 24 hours, the same. An experiment was performed. The results were as follows.

Epoxy equivalent 530 Solid content 0.06 A / B 0.18 Shear strength 7.38 kg / mm ² Strength retention 90% [Example 3] Using the same sizing agent as in Example 1, using a strand dried at 120 ° C for 17 hours. An experiment was performed. The results were as follows.

Epoxy equivalent 390 Solid content 0.016 A / B 0.22 Shear strength 7.40 kg / mm ² Strength retention 90% [Comparative Example] Similar experiment using the same sizing agent as in Example 1 and using a strand dried at 130 ° C for 24 hours. Was done. The results were as follows.

Epoxy equivalent 840 Solid content 0.05 A / B 0.16 Shear strength 7.10 kg / mm ² Strength retention 87% [Effect of the invention] Using glass fiber bundles as reinforcing fibers, high strength, high strength retention after boiling test, Alternatively, it is possible to obtain FRP with a small decrease in strength when repeated stress is applied.

[Brief description of the drawings]

 The figure is a graph showing an infrared absorption spectrum. In the figure, m and n indicate reference lines for determining the absorbance.

Claims (6)

(57) [Claims] 1. A long glass fiber bundle obtained by adding and bundling a sizing agent containing an epoxy resin to a glass fiber, the epoxy resin contained in a solution obtained by reflux-extracting 20 gr of a glass fiber bundle with 25 ml of dioxane for 1 hour. The epoxy equivalent of the resin is 60
Glass fiber bundle characterized by being 0 or less. 2. The glass fiber bundle according to claim 1, wherein the solid content in the extract is 0.02 to 0.5 gr. 3. A glass fiber bundles 50gr the absorbance of the epoxy group in the vicinity of 916 cm ^-1 in the infrared absorption spectrum of the solution which was extracted and washed 2 hours ultrasound using chloroform 300 ml 820 cm ^-1
When the absorbance of adjacent aromatic 2H is A and B, A / B is
The glass fiber bundle according to claim 2, which is 0.2 or more. 4. A long glass fiber bundle obtained by adding and bundling a sizing agent containing an epoxy resin to glass fibers, and extracting 20 g of the glass fiber bundle by refluxing for 1 hour with 25 ml of dioxane. A method for producing a fiber-reinforced resin body, comprising: impregnating a liquid thermosetting resin into a long glass fiber bundle having an epoxy equivalent of 600 or less, and curing the glass fiber bundle in a tensioned state. 5. The method according to claim 4, wherein the solid content in the extract is from 0.02 to 0.5 gr. 6. The glass fiber bundles 50gr the absorbance of the epoxy group in the vicinity of 916 cm ^-1 in the infrared absorption spectrum of the solution which was extracted and washed 2 hours ultrasound using chloroform 300 ml 820 cm ^-1
When the absorbance of adjacent aromatic 2H is A and B, A / B is
6. The production method according to claim 5, which is not less than 0.2.