JPH02255841A - Thermoplastic polyimide foam - Google Patents

Abstract

PURPOSE:To obtain a foam excellent in heat resistance, flame resistance and abrasion resistance and good in secondary processability comprising specified repeating structural units obtained by reacting an ether diamine with a tetracarboxylic acid dianhydride and having a specified apparent density. CONSTITUTION:A thermoplastic polyimide foam comprising repeating structural units of formula I and having an apparent density of 0.02-0.2g/cc. In formula I, X is a direct bond, a 1-10C bivalent hydrocarbon group, a hexafluorinated isopropylidene group, a carbonyl, a thio or a sulfonyl; and R is a tetravalent group selected from among a 2 C or higher aliphatic group, a cycloaliphatic group, a monocyclic aromatic group and a nonfused polycyclic aromatic group composed of aromatic groups bonded directly or through bridging members. The thermoplastic polyimide is a polyimide obtained by reacting an ether diamine of formula II with at least one tetracarboxylic acid dianhydride of formula II.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermoplastic polyimide foam that has excellent heat resistance, flame resistance, abrasion resistance, and good secondary processability.

(Conventional technology) Conventionally, foams made from polymeric materials have been broadly classified into (
1) Foams made from thermoplastic resins, such as polystyrene, polyvinyl chloride, polypropylene, polyethylene, etc., and (2) thermosetting resins, such as polyurethane resins, phenol resins, urea, melamine resins, imide resins, etc. Foams have been developed.

The former foam has excellent wear resistance and secondary processability, so it is widely used in automobiles, architecture, and electronic/electrical fields, taking advantage of the heat resistance, lightness, and other properties of foam. However, there are problems with heat resistance, especially flame resistance. That is,
For example, at high temperatures such as 150° C. or higher, the shape of the foam changes significantly and loses its function as a foam. Also,
When it comes into contact with flame, the surface of the foam burns, and even if flame retardant is added, it immediately melts from the part that comes in contact with flame.
The flowing down causes the foam to melt one after another, eventually resulting in most of the foam disappearing. Due to these drawbacks, it cannot be applied to fields where flame resistance is a problem, such as building materials and aircraft materials.

Further, even in foams made from the latter thermosetting resin, such as polyurethane resin foams, the above-mentioned problem regarding flames has not been solved. In addition, foams made from phenol resin, urea, and melamine resin do not melt when exposed to flames and have excellent flame resistance, but they have poor abrasion resistance as foams, tend to crack, and cause secondary damage. There were problems such as the impossibility of processing, and there were restrictions in terms of use.

Foams made from polyimide resins have also been developed.

For polyimide resins, aromatic carboxylic dianhydrides from International Harvester Co., Ltd. are esterified with alcohol, and diamines are added to create prepolymers, which are then used to create foam-based foams (A) or A representative example is a foam (B) based on polyetherimide (trade name: υLTEM100O, manufactured by General Electric Company, USA) made from a tetracarboxylic dianhydride having an ether bond in the molecule.

The foam (A) is an excellent material, in particular because its shape does not change at temperatures below 200° C., has excellent heat resistance, and does not melt even when exposed to flame. However, the abrasion resistance is insufficient, and secondary processing is not possible, and once it is made into a foam, it cannot be processed and used for a variety of purposes, which is a limitation in this respect. There was also.

Furthermore, although the foam (B) has improved flame resistance, abrasion resistance, and secondary processability, its heat resistance is still not sufficient.

[Problem to be solved by the invention]

The purpose of the present invention is to combine the advantages of foams made from thermosetting resins, such as flame resistance and heat resistance, in addition to the abrasion resistance and secondary processability, which are the advantages of foams made from thermoplastic resins. The aim is to obtain a new polyimide foam for application.

[Means to solve the problem]

As a result of various studies regarding the provision of a new thermoplastic polyimide foam, the present inventors have found that by selecting a specific polyimide, the drawbacks of the conventional products as described above are eliminated, and the resulting material is significantly improved. The present invention was completed based on the discovery that a polyimide foam with excellent performance can be obtained.

That is, the present invention is a thermoplastic polyimide foam having the following turned-over structural unit (I) and having an apparent density of 0.02 to 0.2 g/cc.

(wherein, From aliphatic groups, cycloaliphatic groups, monocyclic aromatic groups, fused polycyclic aromatic groups, and non-fused polycyclic aromatic groups in which an aromatic group is linked to phase I directly or by a bridge member. The thermoplastic polyimide of the present invention described above has the formula (IN)
A polyimide obtained by reacting an ether diamine shown in (wherein, X is the same as before) with one or more tetracarboxylic dianhydrides shown in formula (III), (wherein,
(R is the same as before) The feature is that a diamine having an ether bond is used as a raw material. Specifically, JP-A-Shofi+-143478
, 62-68817, 62-86021 (U.S. Pat. No. 4,847,149), etc., and all thermoplastic polyimides produced by these methods can be used in the present invention. .

A particularly preferred polyimide for producing the thermoplastic polyimide foam of the present invention can be produced using the following raw materials. That is, 4.4°-bis(4
-(3-aminophenoxy)phenyl fusulfide,
4.4′-bis(3-aminophenoxy)phenyl]sulfone, 4,4-bis(3-aminophenoxy)benzophenone, 4,4′-bis(3-aminophenoxy)biphenyl, 2.2-bis(4 -(3-aminophenoxy)phenyl]propane or 2,2-bis(4-(
3-aminophenoxy)phenyl)-1,1,1,:1
, 3.3-hexafluoropropane, and compounds selected from these or a mixture of two or more, and as tetracarboxylic dianhydride, pyromellitic dianhydride, 3.3 °, 4.4'-biphenyltetracarboxylic dianhydride, 3.3°, 4.4'-benzophenonetetracarboxylic dianhydride, 3.3', 4.4°
-diphenyl ether tetracarboxylic dianhydride, p-
phenyleneoxydi(4-phthalic acid) dianhydride,
It is a compound selected from among the types of kowara, either singly or in combination of two or more.

The thermoplastic polyimide that can be employed in the present invention described above is parachlorophenol/phenol (weight ratio 90/10).
in a mixed solvent with a concentration of 0.5 g/100 mj! −
After heating and dissolving in a solvent, the number viscosity measured after cooling to 35°C is 0.35 to 0.65 dll/g, preferably 0.
．． It is in the range of 40 to 0.60 dll/g.

The apparent density of the foam made from Niki Netsucho plastic polyimide is preferably in the range of 0.02 to 0.2 g/cc, and 0.
．． If it exceeds 2 g/cc, it not only impairs the economic efficiency of weight reduction, but also reduces the advantages of the foam, such as cushioning properties, heat insulation properties, and sound insulation properties.

Further, if it is less than 0.02 g/cc, not only the mechanical strength of the foam will decrease, but also flame resistance, abrasion resistance, or secondary processability will deteriorate, which is not preferable.

In this case, the apparent density was calculated by submerging the foam in a measuring cylinder of water, measuring the volume, and dividing the previously measured weight of the foam by its volume. It is something.

In addition, the above appearance shows that among the thermoplastic polyimide foams having a density of 0.02-0.2 g/cc, the structure of the foam is particularly important, and the average diameter of the cells is 0.1-1. It is more preferable that the proportion of closed cells is 50% or more.

Note that the average diameter of the bubbles and the ratio of closed cells are calculated as follows.

Average diameter of bubbles: The average diameter of 10 large, medium, and small bubbles extracted from a cross-sectional photograph of the foam in the thickness direction.

Proportion of closed cells: specified size (40X 401111
11) Place the Zanbul under the water surface, -400+++m
Leave the tube under reduced pressure to Hg for 1 minute. After that, measure the weight before leaving it under the water surface and the weight after leaving it in a reduced pressure state, calculate the water m (vw >) sucked into one foam, and calculate the value calculated by the following formula. be.

Vl; Volume of foam To obtain the thermoplastic polyimide foam of the present invention, it is possible to employ a conventional thermoplastic resin foam extrusion device.

As blowing agents, sublimable substances having a boiling point exceeding 0200°C, such as phthalic anhydride, chemical blowing agents that decompose at around 0200°C, such as trihydrazinotriazine,
Barium azodicarboxylate, dinitrosopentamethylenetetramine, ■Low-boiling organic compounds such as dichlorotrifluoroethane, monochlorobutrafluoroethane, dichlorofluoromethane, monochlorodifluoromethane,
There are hydrates such as acetone that dissociate water at temperatures above 0.200°C, such as oxalic acid dihydrate. Among them, the sublimable substance (■) is good.

The amount of blowing agent used is selected depending on the apparent density of the resulting foam. Specifically, in the case of a sublimable substance, 10.025 to 0.3 II per 100 g of thermoplastic polyimide
lol, in the case of a chemical blowing agent, 0.2 to 10 parts by weight per polyimide ioo, preferably 0.2 to 2 parts by weight, and in the case of a low boiling point organic compound, 0.05 to 0 parts per 100 g of polyimide .51Ilol, and in the case of hydrates, the amount of dissociated water is 0.02 per 100g of polyimide.
The amount can be adjusted to 5 to 0.3 mol and produced by a normal foaming method.

For example, when the blowing agent is solid, the blowing agent and thermoplastic polyimide are both supplied from the hopper of the extruder, the cylinder temperature of the extruder is set to 360 to 440°C, the polyimide and the blowing agent are uniformly kneaded, and then gradually The temperature is lowered, the temperature of the nozzle attached to the tip of the extruder is set at 250 to 370°C, and the extruder is discharged into the atmosphere to form a foam. A layer of fine bubbles can be formed on the surface of the foam discharged from the slit by cooling it with air or by cooling it to 150 to 250°C using a sizing device.

When the foaming agent is a liquid, the foaming agent can be press-injected into the heated thermoplastic polyimide from the middle of the extruder, and then a foam can be produced in the same manner as described above.

Further, the size of the bubbles is controlled by the amount of an inorganic nucleating agent such as talc, silica gel, or a surfactant added. For foams having an average cell diameter of 0.1 to 1 cm, when the blowing agent is a sublimable substance, a low boiling point organic compound, or a hydrate, the above nucleating agent is added to 0.1 parts by weight per 100 parts by weight of polyimide. It is preferable to foam using ~3 parts by weight,
When the foaming agent is a chemical foaming agent, it is preferable to use 0.1 to 1 part by weight of the above-mentioned nucleating agent per 100 parts by weight of polyimide for foaming.

Furthermore, the closed cell ratio is adjusted appropriately depending on the temperature of the mixture in the extruder, cooling conditions after being discharged from the slit of the nozzle, etc., and is set to 50% or more.

There is no problem in using the above blowing agents in combination, and antistatic agents, coloring agents, etc. can also be added as necessary.

(Example) Further, the present invention will be explained in detail by way of examples.

Example 1 A polyimide powder obtained by using pyromellitic dianhydride and 4,4-bis(3-aminophenoxy)biphenyl as a raw material and having a logarithmic viscosity of 0.456117 g was made into a pellet shape using an extruder at a cylinder temperature of 400°C. Extruded. Here, the logarithmic viscosity is a concentration of 0.5 g/l'0 in a mixed solvent of parachlorophenol/phenol (weight ratio 90/'10).
This is a value measured after heating and dissolving in 0 mJl-solvent and then cooling to 35°C.

0.05+++ol of phthalic anhydride per 100g of this polyimide pellet, 10g of polyimide pellet
After mixing 0.7 parts by weight of talc to 0 parts by weight, 30 parts by weight
It was supplied from the hopper of a mmφ extruder. After melting and kneading the extruder cylinder temperature at 380 to 41O<0>C, the temperature was gradually lowered and the temperature of the nozzle attached to the tip of the extruder was controlled at 355<0>C. The resin pressure measured by the pressure gauge attached to the mouthpiece was 10 kg/cm.
1 gold is released into the sizing mold under reduced pressure to a thickness of 5
III11, width]00I! A foam of lII was obtained. The apparent density of the obtained foam was 0.09 g/ce,
The V wall diameter of the bubbles is 0.5 mm, and the closed cell ratio (: back 78
%, shi)・nota.

This foam is 2! nuIIX Cut into 120m111 pieces to use as a sample, place it horizontally on the fulcrum of a 100mm span, and place it on the tumbler in the center between the spans.
I put 100g of 71H on it. In this state, I left it in a constant temperature bath at 200℃ for 1 hour, but there was almost no change.
It was recognized that the foam had excellent heat resistance. Also,
Even when a 25 mm x 120 mm sample was placed horizontally and exposed to indirect flame for 10 seconds using Tehaner, it did not burn or drip.

direction,! , 00m+n disk samples were subjected to the Taber abrasion test (according to JIS-7204). CS-IO was used as the wear wheel, and the test was carried out under a load of 250 g.

The amount of wear sample after repeated 1000 times is 95mg
Met.

This foam was reheated by leaving it in atmosphere F at 380° C. for 1 minute, and then molded in a 0-shaped mold with a male mold key clearance of 41!111. Mold temperature 18
By setting the temperature to 0℃, cracks will not appear on the surface17. Without doing 4, ['J, a good molded product was found.

Example 81 Example 2 Boliimi powder obtained from raw materials such as bis(4-(3-aminophenoxy)phenyl)sulfite and pyromellitic acid dianhydride (logarithmic viscosity 0.46 cl17./g
) was converted to beret (・) in the same manner as in Example 1.

This polyimide and phthalic anhydride were added in an amount of 0.03 mol per 100 g of poly, 1' midoveret. , 9 parts by weight of 0.3 parts of talc were mixed with 100 parts by weight of polyimide pellets, and the mixture was extruded in the same manner as in Example 1. The resulting foam had an apparent density of 0.15 g/cc, an average cell diameter of 0.1 m, and a closed cell ratio of 75%.

In the 200°C test, deformation was observed, indicating the heat resistance, and there was no dripping even when exposed to flame (1).

Even in the deep wear test, it was superior to 135 Ayu, and even when this foam was laminated with an epoxy adhesive, sufficient strength was obtained without the base material breaking at the interface.

Comparative Example 1 In Example 1, the amount of phthalic anhydride mixed was 0.4 mo.
A foam was obtained in the same manner except that the volume was changed to 1.

The apparent density of the obtained foam is 0.0! , 83/c
c, and the bubble diameter is 0. ! oma, closed cell ratio is 66
%Met.

In addition, the Taber abrasion test of foam was repeated continuously for 1000 times.
When carried out twice, the value equivalent to 25,001 mg dropped. Although this foam was laminated using an epoxy adhesive, the base material at the interface was easily destroyed, and sufficient strength of the laminated board could not be obtained.

Comparative Example 2 A foam was extruded in the same manner as in Example 1, except that the temperature of the J gold attached to the tip of the extruder was set to 410°C. The resulting foam had an apparent density of 0.11 g/cc and a closed cell ratio of 45%. This foam was subjected to secondary molding in the same manner as in Example 1, but it cracked at the 0-shaped corner.

Example 3 0.7 to 100 parts by weight of polyimide used in Example 1
The talc in the overlapping section was supplied from a hopper of a 3011II1gφ extruder. Set the extruder cylinder temperature to 380~
Once the polyimide was melted at 410°C, acetone was added from the middle of the extruder to 100g of polyimide.
The resin was press-fitted at a ratio of 0.2 mol and mixed, the temperature of the resin was gradually lowered, and the resin was attached to the tip of the extruder.
The temperature was set to 0°C. ['' Gold was released into a sizing mold under reduced pressure to obtain a foam with a thickness of 5 mm and a width of 100 mm.

The apparent density of the obtained foam was 0.05 g/ce, and the average diameter of the cells was 0.8 m11! So, the closed cell ratio is 62
%Met.

In the heat resistance test shown in Example 1, there was no deformation at 200°C.
Even after conducting a combustion test, there was no dripping.

The result of the abrasion resistance test was 537 mg, and a good molded product was obtained by heat molding in the same manner as in Example 1.

Comparative Example 3 The same procedure as in Example 3 was carried out except that a polyetherimide obtained from 2.2-bis(4-(3゜4-cycarpogycyphenoxy)phenyl)propanedianhydride and m-phenylenediamine was used. Thickness 51T1m, width 10
A foam of 0 mm was obtained. The apparent density of the obtained foam was 0.09 g/cc, and the average diameter of the cells was 0.09 g/cc.
At 5 mtn, the closed cell ratio was 85%.

This foam is 25 x 120 [III! When it was cut into pieces 1 and subjected to the same heat resistance test as in Example 1, it sagged from the center of the fulcrum.

Example 4 A foam was obtained in the same manner as in Example 1 except that 1.8 parts by weight of trihydrazinotriazine was added to 100 parts by weight of polyimide instead of phthalic anhydride. The resulting foam had an apparent density of 0.15 g/ee, an average cell diameter of 0.3 a+m, and a closed cell ratio of 86%.

Even when the foam was subjected to the heat resistance test shown in Example 1, there was no deformation, and there was no dripping during the combustion test. The result of the abrasion test was 57 TIIg. This foam was laminated using an epoxy adhesive, but the base material at the interface did not break and sufficient strength of the laminate was obtained.

Further, this foam was reheated by leaving it in an atmosphere at 380° C. for 1 minute, and then molded using a U-shaped mold with a clearance of 4 mm between the male and female molds. Mold temperature 18
By setting the temperature to 0° C., a good molded product was obtained without causing cracks i1 on the surface.

(Effects of the invention) According to the present invention, it has excellent heat resistance, flame resistance, and abrasion resistance as well as chemical resistance and heat insulation properties, and has excellent moldability, lamination, adhesion, and
Alternatively, a thermoplastic polyimide foam with excellent secondary processability such as surface treatment such as painting is provided.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd. Representative Patent Attorney Tadashi Wakabayashi

Claims (3)

[Claims] (1) A thermoplastic polyimide foam having a repeating structural unit of formula (I) and having an apparent density of 0.02 to 0.2 g/cc. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, X is a direct bond, a divalent hydrocarbon group having 1 to 10 carbon atoms, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, or R is a sulfonyl group, and R is an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, and an aromatic group directly or through a bridge member. (Represents a tetravalent group selected from the group consisting of connected non-fused polycyclic aromatic groups.) (2) Claim 1, wherein the average diameter of the cells in the foam having an apparent density of 0.02 to 0.2 g/cc is 0.1 to 1 mm, and the closed cell ratio in the cells is 50% or more. Polyimide foam as described. (3) A group consisting of a thermoplastic polyimide having the repeating unit of general formula (1), a sublimable substance, a chemical blowing agent that decomposes at around 200°C, a low boiling point organic compound, and a compound that dissociates water at a temperature of 200°C or higher. A method for producing a thermoplastic polyimide foam, comprising extrusion foaming in the presence of a blowing agent selected from the following. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, X is a direct bond, a divalent hydrocarbon group having 1 to 10 carbon atoms, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, or R is a sulfonyl group, and R is an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, and an aromatic group directly or through a bridge member. (Represents a tetravalent group selected from the group consisting of connected non-fused polycyclic aromatic groups.)