JPH06240022A - Prepreg - Google Patents

Abstract

PURPOSE:To obtain a prepreg which gives a molding that can be made lightweight because of low density and that is improved in strength, by laminating a fibrous base material impregnated with a curable resin and a curing agent and/or a thermosetting resin on both sides of a specified fibrous base material. CONSTITUTION:100 pts.wt. component (A) comprising a curable resin and a curing agent and/or a thermosetting resin is mixed with 3-50 pts.wt. expansive thermoplastic resin particles (B) having a diameter of 1mum to 1mm and/or 0.5-20 pts.wt. thermally decomposable foaming agent to give a mixture. 100 pts.wt. fibrous base material (C) having a weight per unit area of 25-300g/m<2> is impregnated with 50-500 pts.wt. of the mixture to give a fibrous base material (D) having a weight per unit area of 100-1000g/m<2>. 100 pts.wt. component C is impregnated with 20-500 pts.wt. component A to give a fibrous base material (E) having a weight per unit area of 30-300g/m<2>. Component E is laminated on both sides of component D.

Description

Detailed Description of the Invention

[0001]

This invention relates to prepregs.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 4-128012 discloses a foamable curable prepreg obtained by impregnating a glass fiber chop mat with a melamine resin and expandable thermoplastic resin particles and drying.

In the case of continuous production of prepreg, a glass fiber chop mat is impregnated with a curable resin, a curing agent and / or a thermosetting resin, and expandable resin particles to produce a thermosetting resin prepreg. The method describes that a fibrous nonwoven may be used as a carrier.

In the continuous production by the above method, a fiber base material is further provided on the other side of the fiber nonwoven fabric used as a carrier from the viewpoint of moldability and strength, and at the same time, a curable resin and a curing agent and / or There is also a method of obtaining a multilayer prepreg by impregnating a thermosetting resin and expandable resin particles.

[0005]

The molded product obtained by heat-molding the prepreg obtained by the above method can have a low density and can be made lightweight, but since it is a foamed layer, it has poor surface strength and a center layer. Since the correlation adhesive strength with the layer adjacent to it is also bad,
The overall strength is also reduced.

[0006]

The inventors of the present invention have made extensive studies in view of the above circumstances, and found that the above problem can be solved by using a prepreg in which a non-foaming layer is laminated adjacent to a foaming center layer. I was found to be done.

That is, the present invention relates to a curable resin, a curing agent and / or
Alternatively, a fibrous base material (C) impregnated with a thermosetting resin (A), expandable thermoplastic resin particles and a pyrolytic foaming agent (B).
As a central layer, and at least both outer sides thereof are substantially filled with expandable thermoplastic resin particles and a thermal decomposition type foaming agent (B) impregnated with a curable resin and a curing agent and / or a thermosetting resin (A). The present invention provides a thermosetting resin multilayer prepreg obtained by laminating a fiber base material (C) which is not contained in the above.

Due to the non-homogeneous structure in which the non-expandable layer is laminated adjacent to the expandable center layer, the foaming system of the center layer causes a decrease in density, that is, a reduction in weight and a thickness,
Further, the non-foaming resin adjacent to the center layer exhibits adhesiveness with the center layer, and thus it is possible to obtain a multi-layer laminated prepreg which is lighter in weight and has excellent strength.

Hereinafter, unless otherwise specified, foaming and expansion are simply referred to as "foaming". A prepreg is generally a resin for reinforced plastics mixed with a curing agent and other components in an appropriate proportion, and is previously impregnated into a fabric-like reinforcing material such as glass cloth to form a non-adhesive semi-cured state. Refers to materials (Taiseisha Publishing Co., Ltd., Polymer Dictionary, 5th edition). That is, it means a material in which the impregnated curable resin component is in the B state.

The B-state is a state between the A-state in which the impregnated curable resin component has not undergone a curing reaction at all and the C-state in which it is completely cured.

In the present invention, as the curable resin, the curing agent and / or the thermosetting resin (A), any of known and commonly used resins can be used. For example, melamine resin, phenol resin, resorcinol resin, urea resin and the like can be used. Can be mentioned.
These resins (A) may be used alone or in combination of two or more kinds.

As the resin (A), a thermosetting resol type phenol resin is preferably used when a cured product having excellent heat resistance is obtained, and a melamine resin is preferable in that the prepreg can be cured at a low temperature in a short time. Is preferably used.

The case where a melamine resin is used as the resin (A) will be described in detail below.

The melamine resin that can be used in the present invention is a condensate containing melamines and aldehydes as essential components, and any known and commonly used one can be used. Of course, at least one selected from the group consisting of ureas, phenols, and resorcinols containing melamine as a main component,
A cocondensation compound obtained by condensing aldehydes can also be used. Of course, a mixture of single condensates such as a mixture of a condensate of melamines and aldehydes and a condensate of phenols and aldehydes can also be used. Further, as the melamine resin, for example, an alkyl etherified melamine resin which is etherified with an alcohol such as methyl alcohol, ethyl alcohol or butyl alcohol can be used.

The method for producing the melamine resin is not particularly limited, but for example, melamines and aldehydes may be added at a molar ratio of aldehydes / melamines of 0.7 to 3.0, if necessary. 80-1 in the presence of a condensation catalyst
The reaction may be performed at 80 ° C for 15 minutes to 5 hours.

The melamine resin is preferably in the form of an aqueous solution or an aqueous dispersion from the viewpoint of excellent impregnation work, and aldehydes / melamines (molar ratio) = 1.5-
An aqueous solution or dispersion of the initial condensate condensed at 2.5 is particularly preferred.

When curing the melamine resin, a compound capable of generating an acid upon heating is usually used together. As the compound that generates an acid capable of curing the melamine resin by heating, any known and commonly used compound can be used. Examples of such a compound include those usually obtained by reacting an acid with a blocking agent.

The acid used at this time may be any acid as long as it can cure the melamine resin, and the blocking agent is added to the acid at room temperature, but the acid is mixed with the acid at the time of curing the melamine resin. Anything can be released. Examples of such a compound include 2-amino-2-methyl-1-
Examples thereof include amine salts of hydrochloric acid such as propanol hydrochloride, ammonium salts of sulfonic acid such as ammonium imidodisulfonic acid, and alcoholic esters of phosphoric acid such as butanol half ester of phosphoric acid. Of these, amine salts of hydrochloric acid or ammonium sulfonic acid salts are preferable.

If necessary, ammonium chloride or ammonium sulfate, which is a known curing agent for melamine resins, may be used in combination with the above compounds.

The component (B) according to the present invention refers to expandable thermoplastic resin particles and / or a thermal decomposition type foaming agent,
They may be used alone or in combination.

In the prepreg of the present invention, these components (B) are embedded / dispersed in the center layer of the prepreg, and in the former expandable thermoplastic resin particles, the curable component (A) starts to cure. The thermal decomposition type foaming agent of the latter also starts to expand at a lower temperature than that of the curable component (A) and starts to decompose at a lower temperature. , Generate gas to form a foam layer.

The expandable thermoplastic resin particles are particles made of a substantially thermoplastic resin having expandability, and any of the known and commonly used ones can be used, but at least at the curing temperature of the prepreg, they are gas. Expandable thermoplastic resin particles in which such a substance is filled inside the shell of the thermoplastic resin are preferable.

When the expandable thermoplastic particles are heated, the shell of the particles is softened, and the gas filled inside expands.
Therefore, by selecting the thermoplastic resin used for the shell portion and the gas filling the inside thereof, it is possible to obtain resin particles that can be expanded at a temperature according to the purpose.

Examples of the thermoplastic resin that constitutes the shell of the expandable thermoplastic particles include vinyl chloride-vinylidene chloride copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-acrylonitrile copolymers, and other chlorinated vinyls. Copolymer of styrene, acrylonitrile copolymer, styrene-methyl (meth) acrylate copolymer,
An acrylic copolymer of methyl (meth) acrylate-ethyl (meth) acrylate copolymer may be mentioned.

As the gas with which the inside of the particles are filled, known and commonly used ones can be used. Examples of such a gas include hydrocarbons such as n-pentane, isopentane, neopentane, n-butane, and isobutane. However, instead of these gases, those that are liquid at room temperature such as CFC can also be used. is there.

The particle size of the expandable thermoplastic resin particles is not particularly limited, but is usually 1 μm to 1 mm, and especially 5 to 50.
It is preferably μm.

When a melamine resin is used as the resin (A), the expandable thermoplastic resin particles are preferably vinylidene chloride-acrylonitrile copolymer having isobutane included therein.

The expandable thermoplastic resin particles have a diameter of 2 to 5 times the diameter before expansion during normal expansion, and the expanded resin particles do not return to their original size.

The mixing ratio of the resin (A) and the expandable thermoplastic resin particles is not particularly limited, but 10 to 30 of the expandable particles are contained in 3 to 50 parts by weight per 100 parts by weight of the resin (A).
It is preferable to use parts by weight.

As the component (B), a thermal decomposition type foaming agent may be used. As the heat-decomposable foaming agent, any known and commonly used one can be used, but a substance that decomposes at least at the curing temperature of the prepreg is preferable.

The thermal decomposition type foaming agent means a substance which decomposes to generate gas when heated. Examples of the gas at this time include nitrogen gas, carbon dioxide gas, carbon monoxide gas, and ammonia gas. Examples of the thermal decomposition type foaming agent include azodicarboxylic acid amide, azoisobutyronitrile, dinitrosopentamethylenetetramine, 4,4′-oxybisbenzosulfonylhydrazide, paratoluenesulfonylhydrazide, sodium hydrogencarbonate and hydrogencarbonate. Examples include potassium and ammonium hydrogen carbonate.

The mixing ratio of the resin (A) and the thermal decomposition type foaming agent is not particularly limited, but 0.5 to 20 parts by weight, preferably 1 to 1 part of the thermal decomposition type foaming agent per 100 parts by weight of the resin (A).
5 parts by weight is good.

As the component (B), it is easy to make the gas cell diameter of the obtained foam small and uniform, and it is possible to obtain a foam having slightly excellent strength and elastic modulus, and the resilience to long-term stress. From the viewpoint of excellence, it is preferable to use expandable thermoplastic resin particles.

Various foam stabilizers may be used for enhancing the dispersion of the component (B) and controlling the foaming state and the closed cell ratio of the obtained cured product. As such a foam stabilizer,
Any of hydrocarbon-based, silicone-based, and fluorine-based can be used, and the polarity thereof may be any of nonion, cation, and anion.

When a thermally decomposable foaming agent is used as the component (B), it is necessary to separately control the size of the cell and the variation thereof with a foam stabilizer as described above. Workability tends to be inferior as compared with the case where a foam is produced.

If desired, a plasticizer, a filler, a flame retardant, a defoaming agent, etc. may be added to these components (A) and (B).

As the fiber base material (C), polyester,
Acrylic, nylon, polyethylene, polypropylene,
Nonwoven fabrics and woven fabrics obtained by wet and dry spinning synthetic fibers such as vinylon and polyurethane, inorganic fibers such as carbon and glass, and natural fibers such as cotton, hemp, wool and silk can be used.
If necessary, a mixed paper of the above fibers may be used. The basis weight is not particularly limited, but is 25 to 300 g.
/ M ² is preferable.

The method for producing the prepreg according to the present invention is not particularly limited, but it can be produced, for example, by the following steps.

A mixture of the expandable resin particles and / or the pyrolytic foaming agent (B) and the curable resin component (A) is prepared. If necessary, a foam stabilizer and a release agent are added (formulation 1). A resin component (A) is prepared. A release agent is added if necessary (formulation 2).

The fibrous base material (C) is impregnated in the bath of Formulation 1 above. The fibrous base material (C) is impregnated in the bath of the above Formulation 2.

The method of impregnation is not particularly limited, and a roll coater, bar coater, mangle roll, spray or the like may be used. As the fiber base material, a roll-shaped base material is preferable because it has excellent continuous productivity.

The sheet-shaped resin-impregnated base material obtained in the above and steps is dried at a temperature at which the resin (A) does not cure.

The impregnated base material obtained in the above steps and may be conveyed simultaneously or independently during the production of the prepreg. In terms of excellent continuous productivity, it is preferable to convey them at the same time, and both sides of the impregnated base material obtained in the step before the drying step are conveyed simultaneously with the impregnated base material obtained in the step, and after drying for a predetermined time. It is better to cut it into a multi-layer prepreg.

In the case of transporting alone, after the impregnated base material is dried in advance for a predetermined time, it is wound, and at the end of the step of drying the impregnated base material, that is, at the exit of the dryer, There is a method in which a dried impregnated base material is joined to both sides thereof by a chemical / physical means such as an adhesive or a stapler and cut to a predetermined length to form a multi-layer prepreg.

Here, the resin (A) component and the component (B) impregnated in the fiber base material (C) as the central layer are 50 to 500 parts by weight per 100 parts by weight of the fiber base material (C), and The weight per unit area is preferably 100 to 1000 g / m ² .

Further, the resin component (A) impregnated into the fiber base material (C) which is both outer layers is 20 to 500 parts by weight and the basis weight is 30 to 3 per 100 parts by weight of the fiber base material (C).
00 g / m ² is preferred.

The basis weights of the center layer and both outer layers may be appropriately selected within the range of the basis weight described above, and any basis weight may be molded. Particularly in terms of strength, it is effective that the weights of both outer layers are relatively high.

In the prepreg of the present invention, the center layer may be a foam layer and at least both outer layers thereof may be non-foam layers. Therefore, not only the three-layer structure of non-foamed layer / foamed layer / non-foamed layer but also seven-layered structure of non-foamed layer / foamed layer / non-foamed layer / foamed layer / non-foamed layer / foamed layer / non-foamed layer. May be.
When the number of layers is increased, it is preferable that the outermost layer exposed on the surface is a non-foamed layer because the powder falling phenomenon is unlikely to occur.

The component (B) is preferably foamed before the resin component (A) is completely cured (in a C state), and may be partially foamed or entirely foamed in this drying step. Good. The foaming state of the component (B) can be adjusted by selecting the kind of the foaming agent, the drying temperature and the time, if necessary.

For example, when a melamine resin is used as the resin component (A), the drying temperature at this time is usually 90.
It is 3 to 6 minutes at -120 ° C. Drying at this time is usually performed in a circulating heat dryer.

The thermosetting resin prepreg thus obtained through the steps (1) to (4) may be covered with a synthetic resin sheet if necessary and may be stored while being shielded from the outside air. The prepreg thus obtained can be stably stored for 1 month without being cured even when stored at 40 ° C.

Although the total weight of the prepreg of the present invention is not limited, it is generally 400 to 1000 g.

The thermosetting prepreg thus obtained is heated at the curing temperature of the thermosetting resin after removing the sheet for shutting off the outside air, if necessary, maintaining the desired shape. , Expand the expandable thermoplastic resin particles,
A cured product can be obtained by decomposing the thermal decomposition type foaming agent to generate a gas and curing the composition.

The curing conditions at this time vary depending on the resin component (A) used, but for example, a resole type phenol resin is at 190 to 250 ° C. for 30 to 120 seconds, and a melamine resin is at 140 to 210 ° C. for 30 to 90 seconds. Is. As can be seen from this curing temperature, it is preferable to use a melamine resin when it is desired to save productivity and energy consumption of the cured product, or when laminating with a base material that is weak against high temperature, which is performed later, for example.

The curing at this time is usually carried out by placing the prepreg in a heated mold, degassing as necessary, and molding by press molding. (Hereinafter, this is referred to as thermocompression molding.) If necessary, the cured body is cooled by blowing air, water, or the like.

The cured product thus obtained may have a support laminated on at least one surface thereof. Examples of the support used in this case include a synthetic resin film, a nonwoven fabric, a flexible polyurethane foam layer of a laminate of a synthetic resin film and a flexible polyurethane foam, and a flexible polyurethane foam layer of a laminate of a nonwoven fabric and a flexible polyurethane foam. In addition, paper, metal foil, etc. can also be used.

At this time, if necessary, a hot melt adhesive may be used for bonding the support and the prepreg. As the hot melt adhesive, various types such as polyester type, polyamide type, polyolefin type, polyvinyl chloride-polyvinyl acetate type, polyurethane type and acrylic type can be used.

Further, as one of the features of the present invention, since the expandable thermoplastic resin particles and / or the pyrolytic foaming agent (B) are not substantially contained in both outer layers, the molded product does not fall off. It can be mentioned. That is, JP-A-4-128012 describes that a glass chop mat is impregnated with a curable resin and a curing agent and / or a thermosetting resin and expansive resin particles. It is also described that it may be used as a carrier, but in any case, all the layers contain expansive particles and / or the heat-decomposable foaming agent (B), so that powder falling is inevitable.

The cured product of the prepreg of the present invention may be used as it is or laminated, or as a laminate of the prepreg and other base material, for example, sound insulating building board material, cushion material, packing material, sound absorbing material, heat insulating material, It can be used for storage containers, wall materials, helmet innerwear, protectors, vehicles, automobile interior materials, ships, wall materials for aircraft, etc.

[0060]

[Experimental Example] Hereinafter, the prepreg of the present invention will be described by taking a wall material which is an example of a final product as an example. Hereinafter, "parts" means "parts by weight" and "%" means "% by weight" unless otherwise specified.

Example 1 1620 g of 37% aqueous formaldehyde solution, 1260 g of melamine, and 83 g of 48% aqueous sodium hydroxide solution were placed in this order in a flask equipped with a reflux condenser, and the temperature was raised to 90 ° C. over 1 hour. The dehydration condensation reaction was carried out at this temperature for 4 hours, and then cooled to room temperature. A 48% sodium hydroxide aqueous solution was added to this to adjust the pH to 10. The resulting melamine resin initial condensate aqueous solution had a solid content of 55.4%,
The pH was 10 and the viscosity was 23 cps.

100 parts of the above melamine resin, 1 part of 2-amino-2-methyl-1-propanol hydrochloride, vinylidene chloride-acrylonitrile copolymer as a shell, and isobutane contained in the shell, and the expansion thereof is 10 μm. 15 parts by weight of the thermoplastic resin particles were mixed. This is simply called a mixture (impregnation bath).

100 parts of the above melamine resin was mixed with 1 part of 2-amino-2-methyl-1-propanol hydrochloride. This is simply called a mixture (impregnation bath).

100 g / m ² of polyester non-woven fabric was immersed in an impregnation bath and passed through a squeezing roll to adjust the impregnation amount so that the solid content of the solid was 450 g / m ² .

A glass nonwoven fabric of 30 g / m ² was dipped in an impregnation bath and passed through a squeezing roll, and the impregnation amount was adjusted so that the total solid content weight was 75 g / m ² .

A 30 g / m ² glass non-woven fabric was dipped in another similar impregnation bath, passed through a squeezing roll, and the impregnation amount was adjusted so that the total solid content weight was 75 g / m ² .

The resin-impregnated base material obtained as described above and the resin-impregnated base material obtained as described above are stacked and conveyed on the upper and lower sides (both outer sides) of the resin-impregnated base material obtained as described above.
A sheet-shaped prepreg was obtained by heating for 5 minutes in a hot-air circulation type dryer adjusted to ℃.

The prepreg was molded for 1 minute at a pressure of 5 kg / cm ² with a molding die heated to 180 ° C. The bending strength and weight of the obtained molded body (cured body) were measured. The results are shown in Table-1. The molded body has a thickness of 4 mm, a density of 0.18 g / cm ³ , and a bending strength of 65 kg.
/ Cm ² , and the elastic modulus was 6000 kg / cm ² .

The prepreg before molding was stored in a constant temperature room at 40 ° C. for 30 days and then molded by the same method, but with a thickness of 3.9.
mm, density 0.17 g / cm ³ , bending strength 60 kg / c
The elastic modulus was m ² and the elastic modulus was 5800 kg / cm ² , and the physical properties of the molded product were hardly deteriorated during prepreg storage.

Example 2 In Example 1, the upper and lower layers of the glass nonwoven fabric and the mixture had a solid content of 100 g / m ² , and the lower layer had a solid content of 50 g.
/ M ² except that the prepreg was obtained in the same manner as in Example 1 and molded under the same conditions.

The bending strength and weight of the obtained molded product (cured product) were measured. The results are shown in Table-1. Also the molded article, a thickness of 4 mm, density 0.18 g / cm ^3, flexural strength 85 kg / cm ^2, an elastic modulus of 7600kg / cm ^2.

Example 3 In Example 1, the solid content weight of the polyester nonwoven fabric as the central layer and the mixture was 400 g / m ² , and the solid content weight of the upper and lower glass nonwoven fabric and the mixture was 100 g / m ^2.
A prepreg was obtained in the same manner as in Example 1 except that the above was used, and was molded under the same conditions.

The bending strength and weight of the obtained molded body (cured body) were measured. The results are shown in Table-1. Also the molded article, a thickness of 4 mm, density 0.19 g / cm ^3, flexural strength 75 kg / cm ^2, an elastic modulus of 6800kg / cm ^2.

Comparative Example 1 Instead of 100 g / m ² of polyester nonwoven fabric, 200
The same operation as in Example 1 was performed except that the glass chop mat of g / m ² was changed, and the upper and lower glass nonwoven fabrics were all impregnated with the mixture, and the solid content weight of the solid was adjusted to 600 g / m ^2. Then, a prepreg was obtained, and this prepreg was molded under the same conditions as in Example 1.

The bending strength and weight of the obtained molded product (cured product) were measured. The results are shown in Table-1. The molded body had a thickness of 4 mm, a density of 0.15 g / cm ³ , a bending strength of 40 kg / cm ² , and an elastic modulus of 5000 kg / cm ² .

Comparative Example 2 Example 1 except that 100 g / m ² of polyester non-woven fabric and 30 g / m ² of glass non-woven fabric were all impregnated in the mixture and the solid weight of the solid was adjusted to 600 g / m ^2. The same operation was performed to obtain a prepreg, and this prepreg was molded under the same conditions as in Example 1.

The bending strength and weight of the obtained molded product (cured product) were measured. The results are shown in Table-1. The molded body had a thickness of 4 mm, a density of 0.16 g / cm ³ , a bending strength of 45 kg / cm ² , and an elastic modulus of 5400 kg / cm ² .

[0078]

[Table 1] Table-1 ┌────────┬────┬────┬────┬────┬────┐ │ │ Example 1 │ Example 2│Example 3│Comparative Example 1│Comparative Example 2│ ├────────┼────┼────┼────┼────┼────┤ │ Weight (g / m ² ) │ 605 │ 610 │ 613 │ 603 │ 608 │ ├────────┼────┼────┼────┼────┼── ──┤ │ Bending strength (kg / cm ² ) │ 65 │ 85 │ 75 │ 40 │ 45 │ ├────────┼────┼────┼────┼── ──┼────┤ │Presence or absence of powder drop │ None │ None │ None │ Yes │ Yes │ └────────┴────┴────┴────┴ ────┴────┘

As can be seen by comparing Example 3 in Table 1 with Comparative Examples 1 and 2, when the cured products having substantially the same weight are compared, the cured product of the prepreg of the present invention shows the conventional prepreg. It is superior in strength to the cured product of No. 1, and it is clear that the powder falling phenomenon does not occur.

[0080]

EFFECTS OF THE INVENTION The prepreg of the present invention has a foamable layer at the center and a non-foamable layer at least on both outer sides thereof, so that the cured product thereof is excellent in strength.

Claims (3)

[Claims] 1. A fiber base material (C) impregnated with a curable resin, a curing agent and / or a thermosetting resin (A), and expandable thermoplastic resin particles and / or a thermal decomposition type foaming agent (B). ) As a central layer, and at least both outer sides thereof are impregnated with a curable resin and a curing agent and / or a thermosetting resin (A), expandable thermoplastic resin particles and / or a thermal decomposition type foaming agent (B). A thermosetting resin multilayer prepreg obtained by laminating a fiber base material (C) which does not substantially contain the above. 2. The curable resin and the curing agent and / or the thermosetting resin (A) impregnated in the fiber base material (C) on both outer sides are 20 to 500 per 100 parts by weight of the fiber base material (C). 2. The weight part and the basis weight are 30 to 300 g / m < ² >.
The listed prepreg. 3. The prepreg according to claim 1, wherein the curable resin, the curing agent and / or the thermosetting resin (A) is a resol type phenol resin or a melamine resin.