WO2006114776A1

WO2006114776A1 - Surfactant for phenolic foam

Info

Publication number: WO2006114776A1
Application number: PCT/IE2005/000044
Authority: WO
Inventors: Ruud Zeggelaar
Original assignee: Kingspan Holdings (Irl) Limited
Priority date: 2005-04-27
Filing date: 2005-04-27
Publication date: 2006-11-02
Also published as: GB0723086D0; EP1874855A1; CN101184800A; CN101184800B; GB2440493A; GB2440493B

Abstract

A surfactant for phenolic foam comprises a castor oil-ethylene oxide adduct wherein the ethylene oxide has more than 20 moles but less than 40 moles added to 1 mole of castor oil. The thermal insulation performance of the phenolic foam is good and does not vary greatly. The phenolic foam has high thermal insulation performance and a low moisture permeability coefficient.

Description

"Surfactant for Phenolic Foam aad-α^Btø@ess-fe^feed«efflg-Phenolte4^;:eam-"

Introduction

This invention relates to a surfactant for phenolic foam, phenolic foam products and a process for producing phenolic foam.

Phenolic foam is used in insulation applications for construction materials because of its superior thermal insulation and fire resistance characteristics.

It is important that phenolic foam cell size is fine, and that it has closed cell structure to enhance the thermal insulation performance of phenolic foam products. To be able to produce phenolic foam, surfactant needs to be present to act as a cell stabilisation agent.

A process for producing phenolic foam using a castor oil-ethylene oxide adduct is known. Hereinafter, ethylene oxide is referred to as EO.

JP-A-61 -268733 describes a castor oil-EO adduct in which 2 to 20 moles of EO is added to 1 mole of castor oil. JP-A-63-039933 describes a castor oil-EO adduct in which 40 to 90 moles of EO is added to 1 mole of castor oil.

However, it has become clear that known castor oil-EO adducts have the following problems:

(1) When the EO molar number of the castor oil-EO adduct is from 2 to 20 moles per mole of castor oil, and it is used as a surfactant, the thermal insulation performance of the phenolic foam obtained is inferior. Moreover, if the ratio of the number of moles of EO added per mole of castor oil in the adduct varies slightly, the thermal insulation performance of the phenolic foam obtained can vary significantly.

Therefore it is difficult to obtain phenolic foam with a predetermined thermal insulation performance. Also, the phenolic foam obtained has a higher moisture permeability coefficient.

(2) When the EO molar number in the castor oil-EO adduct is from 40 to 90 moles and the adduct is used as a surfactant, the cost of producing the castor oil-EO adduct not only is higher because of the use of the higher molar number of the EO added, but also the thermal insulation performance of the phenolic foam obtained is inferior and its moisture permeability coefficient becomes higher.

An objective of the present invention is to provide a surfactant for phenolic foam that overcomes the above-mentioned problems. Additionally, an objective of the present invention is to provide a process for efficiently producing the said phenolic foam in which the surfactant is used.

Statements of Invention

The invention described herein achieves the above stated objectives.

We have unexpectedly found that when a castor oil-EO adduct has more than 20 moles but less than 40 moles of EO added per 1 mole of castor oil and such an adduct is employed as a surfactant, the phenolic foam so obtained has improved thermal insulation performance. Even though the molar ratio of the EO present in the castor oil-EO adduct has varied within a range of more than 20 moles but less than 40 moles of EO per 1 mole of castor oil, the thermal insulation performance of the phenolic foam obtained does not greatly vary, and additionally the moisture permeability coefficient of the phenolic foam is kept low. The present invention is based on such findings. According to the invention there is provided a surfactant for phenolic foam characterised by a castor oil-ethylene oxide adduct wherein more than 20 moles but less than 40 moles of ethylene oxide are added per 1 mole of castor oil

The invention also provides a phenolic foam comprising phenolic resin, blowing agent, surfactant and catalyst, characterised in that the surfactant is a castor oil- ethylene oxide adduct wherein more than 20 moles but less than 40 moles of ethylene oxide are added to 1 mole of castor oil

The content of the castor oil-ethylene oxide adduct may be from 1 to 5 parts by weight relative to 100 parts by weight of the phenolic resin.

The phenolic foam may be prepared by curing a phenolic resin in which the molar ratio of phenol to formaldehyde is typically between 1 : 1.5 and 1 : 2.5; the weight average molecular weight is in the range from 700 to 2,000; and the number average molecular weight is in the range from 300 to 700

The thermal conductivity of the phenolic foam is preferably equal to or less than 0.022 W/m.K

The moisture permeability coefficient for a thickness of 25mm is preferably not more than 60 ng/(m².s.Pa).

The invention also provides a process for producing phenolic foam by preparing a foamable phenolic resin composition that comprises phenolic resin, surfactant, plasticiser, blowing agent, and catalyst, delivering the resin composition onto a continuously running substrate, and passing through a heated zone to produce phenolic foam as the phenolic foam is moulded into a predetermined shape. The phenolic foam is characterised in that the surfactant used is a castor oil-ethylene- oxide adduct wherein more than 20 moles but less than 40 moles of ethylene oxide are added to 1 mole of castor oil. Detailed Description

The surfactant of the present invention is a castor oil-EO adduct that is obtained by adding more than 20 moles but less than 40 moles of EO to 1 mole of castor oil. The surfactant has a hydrophobic segment mainly comprising a long hydrocarbon chain from castor oil and a hydrophilic segment mainly comprising polyoxyethylene (EO) chemical linkages. It is presumed that a well-balanced molecular structure formed from both the hydrophobic and the hydrophilic segment optimises the surface activity of the surfactant, helps make phenolic foam cell diameter small, and the cell walls of the phenolic foam more flexible. Thereby cracks in the cell walls are less likely to occur.

Therefore, when the surfactant of the present invention is used in phenolic foam, excellent thermal insulation performance is obtained. Even when the molar ratio of

EO to castor oil is varied, the thermal insulation performance of the phenolic foam obtained does not vary greatly. Additionally, the permeability coefficient of the phenolic foam remains low.

One preferred embodiment for practising the present invention will be described below.

The surfactant of the present invent is characterised by the castor oil-EO adduct in which more than 20 moles but less than 40 moles of EO are added to 1 mole of castor oil. Castor oil is a non-drying oil derived from seeds of castor oil beans that contain a relatively large amount of unsaturated acids such a ricinoleic acid, oleic acid, and linoleic acid and a small amount of saturated acids such as stearic acid and dioxystearic acid. To 1 mole of this castor oil are added more than 20 moles but less than 40 moles of EO. As presented above, when the molar number of EO is more than 20 moles, but less than 40 moles, and this is added to 1 mole of castor oil, then a well-balanced molecular structure of hydrophobic, long chain hydrocarbon castor oil with hydrophilic EO segments is obtained. The surfactant then has favourable surface activity. The effect of using this surfactant is that cell diameter of the phenolic foam is kept fine, flexibility is imparted to the cell walls of the phenolic foam and crack occurrence in the cell walls can be prevented. A preferred molar number of EO to add to 1 mole of castor oil is between 21 and 38. The surfactant of the present invention may be used either alone or in combination with another surfactant. Examples of other surfactants that may be used are shown later.

The phenolic foam of the present invention will be described next.

The phenolic foam comprises phenolic resin, blowing agent, surfactant and a catalyst and is characterised in that the surfactant used is a castor oil-ethylene oxide adduct wherein more than 20 moles but less than 40 moles of ethylene oxide are added to 1 mole of castor oil.

A preferred phenolic resin used in the present invention is a resole resin (hereinafter, referred also to as phenolic resin material) that is obtained by the reaction of a phenol such as cresol, xylenol, para-alkylphenol, para-phenylphenol, resorcinol, and the like with an aldehyde such as formaldehyde, paraformaldehyde, furfural, acetaldehyde and the like under a catalytic amount of an alkali such as sodium hydroxide, potassium hydroxide, calcium hydroxide, or aliphatic amines like trimethylamine, and triethylamine. These chemical constituents are used in ordinary resole production but are not limited to those just mentioned here. The molar ratio of phenol groups to aldehyde is not especially limited. It is preferable that the molar ratio of phenol to an aldehyde is from 1 : 1 to 1 : 3, more preferably from 1.5 to 2.5, and particularly preferable approximately 1 : 2. A preferable molecular weight for a phenolic resin material is from 400 to 3,000, and more preferably from 700 to 2,000 in terms of weight average molecular weight. On the other hand, the number average molecular weight is from 150 to 1,000, and more preferably from 300 to 700. Blowing agent selection is not especially limited and blowing agents in the public domain are employed in the present invention. These include saturated aliphatic hydrocarbons with low boiling points such as butane, pentane, hexane, or heptane ether such as isopropyl ether a fluoride-containing hydrocarbon compound such as trichloromonofluoromethane, trichlorotrifluoroethane or a mixture thereof.

As surfactant, the castor oil-EO adduct mentioned above, in which more than 20 moles but less than 40 moles of EO is added to 1 mole of castor oil, is employed is an essential component of the present invention. Besides this adduct, a dimethyl polysiloxane-polyoxy alkylene copolymer like dimethyl polysiloxane-polyoxy ethylene copolymer, or a castor oil-polypropylene oxide adduct and so on may be used.

As catalyst, an inorganic acid such as sulphuric acid or phosphoric acid, or an organic acid such as benzene sulfonic acid, xylene sulfonic acid, paratoluene sulfonic acid, naphthol sulfonic acid, phenol sulfonic acid and so on are used.

A plasticiser may be present the phenolic foam of the present invention such as a sulfonamide, a polyester polyol and the like.

The weight addition of the castor oil-EO adduct relative to 100 parts by weight of phenolic foam is preferably from 1 to 5 parts by weight, and more preferably from 2 to 4 parts by weight. If the content of the castor oil-EO adduct is less than 1 part by weight, uniform cells cannot be obtained in the foam. On the other hand, if more than 5 parts by weight of the castor oil-EO adduct is used, the production cost and the water-absorbing capacity of the foam is increased.

The phenolic foam of the present invention has a thermal conductivity of under 0.022 W/m.K preferably. Phenolic foam with a thermal conductivity more than 0.022 W/m.K is less efficient in terms of thermal insulation performance. For the present invention, the phenolic foam preferably has a moisture permeability coefficient of below 60 ng/(m².s.Pa) for a thickness of 25mm. Phenolic foam with a moisture permeability coefficient above 60 ng/(m².s.Pa) for a thickness of 25mm is undesirable.

The facing materials used are not limited. They can be fibrous materials. They include a non-woven fabric, paper and the like made from a natural fibre, synthetic fibre, inorganic fibre, etc. The facing materials can also be metallic or plastic foils or sheets, with or without a suitable primer coating or fibrous interlayer to enhance adhesion.

A process for producing phenolic foam comprises preparing a foamable phenolic resin composition that includes phenolic resin, surfactant, plasticiser, blowing agent, and a catalyst. In accordance with the process for producing phenolic foam of the present invention the foam is characterised in that the surfactant present is a castor oil-ethylene oxide adduct in which more than 20 moles but less than 40 moles of EO are added to 1 mole of castor oil.

In the process for producing phenolic foam of the present invention, for example, the described castor oil-EO adduct surfactant is then added to the phenolic resin composition.

A plasticiser such as polyester polyol is optionally mixed into the phenolic resin also.

The phenolic resin composition obtained is pumped to a high speed mixer head where it is introduced to and mixed with blowing agent and acid catalyst to prepare a foamable phenolic composition.

According to the process for producing phenolic foam of the present invention, during manufacture, the said foamable phenolic resin composition is discharged on to a running carrier and passed through a heated zone for foaming and moulding into the desired phenolic foam products. In more detail, the said resin composition is discharged on to a running conveyor belt into the heated oven typically at 60 to 100°C for approximately 2 to 15 minutes. The top of the foaming composition is pressed down with another conveyer belt, while the thickness of the foam is controlled to the required predetermined thickness. The phenolic foam leaving the oven is then cut to a predetermined length.

The phenolic foam of the present invention is formed and moulded by using the following processes in which the said foamable phenolic resin composition thus prepared is (1) discharged on to a continuous conveyer, (2) warmed and foamed partially, (3) placed in a pressurised mould, (4) discharged into a mould to give a foaming block, or (5) charged into one or more of closed cavities under high pressure and so on.

Evaluation methods for testing the physical properties of the phenolic foam are described below. Various samples of phenolic foam were tested using these evaluation methods.

(1) Thermal Conductivity (abbreviated as TC) A test piece of length 300 mm and width 300mm was placed between a high temperature plate with a temperature of 30°C and a low temperature plate with a temperature of 10°C in a thermal conductivity test instrument (Type HC-074 304, Koei Seiki Co., Ltd.) in which the thermal conductivity, TC, of the test pieces was measured according to JIS A 1412.

(2) Moisture Permeability Coefficient (abbreviated as MPC) for a thickness of 25mm This property was measured using JIS A 9511.

Three disc shape test pieces are cut from a phenolic foam board with a thickness of 25mm and a diameter of 65 mm. The dimension of the test piece had an accuracy of 0.1 mm and the moisture permeability area of water vapour was calculated as 0.05 cm2.

Moisture permeability coefficient, (MPC), for a thickness of 25mm is

m2 - ml x 1 x _L _

(T2-TDA (P2-P1) 25

Where, ml, m2: is the weight (ng) each for time Tl or time T2

Tl, T2: is the time (s) each of the weight ml or m2

A : is the moisture permeability area (m2) of water vapour of each test piece

Pl : is the vapour pressure of water (Pl= 0 Pa) in a flask P2 : is the vapour pressure (1404.4 Pa) of a thermostatic tank t : is the thickness (mm) of a test piece

Reference Example - The synthesis of a castor oil-EO adduct

932 g (1 mole) of castor oil and 5.9 g of sodium hydroxide as a catalyst were put into a two-litre stainless steel reactor vessel fitted with a stirrer and a thermostat. Under nitrogen atmosphere, 968 g of EO, (22 moles), was introduced into the vessel. The reactants were held for one hour with gauge pressure at 1 to 4 kgf/cm² and the temperature at 140⁰C to 16O⁰C. The reaction mixture was treated with an adsorbing material, (Kyoward 600, supplied by Kyowa Chemical Kogyo Co Ltd) to adsorb the catalyst and obtain an eluate. The eluate was evaporated at 120⁰C for 2h under a pressure of about 20 mmHg and the residual liquid was dried to obtain a castor oil- EO adduct in which 22 moles of EO had been added to one mole of castor oil. In the same manner as above, but using different molar numbers of EO, castor oil- EO adducts were obtained in which 10, 30, 37, 50 or 75 moles of EO had been added to 1 mole of castor oil.

Examples

The present invention will be explained in details by the Examples that follow, but is not limited only to the Examples and the Comparative Examples.

Example 1

To 100 parts by weight of a resole resin, PF-329, ( molar ratio of phenol : formaldehyde is 1 : 2.0, weight average molecular weight 1400, and number average molecular weight 500, produced by Asahi Organic Chemicals Industry Co. Ltd.), is added 3.5 parts of castor oil-EO (22 moles) adduct as a surfactant as described in the Reference Example, The resin blend is pumped to a high speed mixer and 20 parts by weight of a mixture of para-toluene sulfonic acid and xylene sulfonic acid ( weight ratio was 2 :1) as a catalyst and 8 parts by weight of pentane as a blowing agent, are added to give a foamable phenolic resin composition. The resin composition is discharged into a moulding frame laid with a glass fibre non-woven fabric. Foaming commenced, and the sample was held at 80°C for 10 minutes hours in an oven to give cured phenolic foam. The dimensions of the foam sample obtained are 300mm length, 300mm width and 25mm thickness.

Example 2 A phenolic foam was prepared by the same manner as in Example 1 except that the molar number of the EO used was changed to 30.

Example 3

A phenolic foam was prepared by the same manner as in Example 1 except that the molar number of the EO used was changed to 37. Comparative Example 1

A phenolic foam was prepared by the same manner as in Example 1 except that the molar number of the EO used was changed to 10.

Comparative Example 2

A phenolic foam was prepared by the same manner as in Example 1 except that the molar number of the EO used was changed to 50.

Comparative Example 3 A phenolic foam was prepared by the same manner as in Example 1 except that the molar number of the EO used was changed to 75.

The results for thermal conductivity and moisture permeability coefficient for 25mm thick phenolic foam samples obtained from the Examples and Comparative Examples are shown in Table 1.

Table 1

As shown in Table 1, the Examples from 1 to 3 corresponding to castor oil-EO adducts in which 20, 30, or 37 moles of EO are respectively added to 1 mole of castor oil have a low thermal conductivity falling within the range from 0.0187 to 0.0192 W/m K. It means that each of these foam samples have favourable thermal conductivity for insulation applications.

On the other hand, the Comparative Examples 1 to 3 show thermal conductivity within the range 0.0230 to 0.0280 W/m.K. These results are for castor oil-EO adducts in which 10, 50, or 75 moles each of EO had been added to 1 mole of castor oil. The thermal conductivity results for Comparative Examples 1 to 3 are inferior to results found for Examples 1 to 3. Examples 1 to 3 corresponding to castor oil-EO adducts in which 20, 30, or 37 moles each of EO were added to 1 mole of castor oil have a low moisture permeability coefficient per 25mm thickness that is within the range 40 to 43 ng/(m².s.Pa). This means that each foam sample was satisfactory in terms of moisture permeability coefficient as well as for thermal conductivity. In the Comparative Examples 1 to 3, the respective moisture permeability coefficient values were higher within the range 65 to 70 ng/(m².s.Pa).

From the results, it is obvious that the molar number of EO in an castor oil-EO adduct should be more than 20 moles but less than 40 moles of EO relative to 1 mole of castor oil to obtain optimised thermal conductivity.

Phenolic foam in which the castor oil-EO adduct of the present invention is used as a surfactant provides favourable thermal insulation performance. Even though the molar addition number of EO to castor oil is varied, the thermal insulation performance of the phenolic foam obtained does not vary greatly. Further, having a low moisture permeability coefficient, the phenolic foam of the present invention is suitable for use in the field of construction materials

The invention is not limited to the embodiments described which may be varied in detail.

Claims

1. A surfactant for phenolic foam characterised by a castor oil-ethylene oxide adduct wherein there is more than 20 moles but less than 40 moles of ethylene oxide added to 1 mole of castor oil.

2. Phenolic foam comprising phenolic resin, blowing agent, surfactant and catalyst, characterised in that the surfactant is a castor oil-ethylene oxide adduct wherein there is more than 20 moles but less than 40 moles of ethylene oxide added to 1 mole of castor oil.

3. Phenolic foam as claimed in claim 2, wherein the content of the castor oil- ethylene oxide adduct is from 1 to 5 parts by weight per 100 parts by weight of phenolic resin.

4. Phenolic foam as claimed in claim 2 or 3, prepared by curing a phenolic resin in which the molar ratio of phenol to formaldehyde is in the range from 1 : 1.5 to 1 : 2.5 ; the weight average molecular weight is in the range from 700 to 2,000; and the number average molecular weight is in the range from 300 to 700.

5. Phenolic foam as claimed in any of claims 2 to 4, wherein the thermal conductivity is equal to or less than 0.022 W/m.K.

6. Phenolic foam as claimed in any of claims 2 to 5, wherein the moisture permeability coefficient for a thickness of 25mm is not more than 60 ng/(m².s.Pa).

7. A process for producing phenolic foam by preparing a foamable phenolic resin composition that comprises phenolic resin, surfactant, plasticiser, blowing agent, and catalyst, delivering the resin onto a continuously running substrate, and passing through a heated zone to produce phenolic foam as the phenolic foam is moulded into a predetermined shape, characterised in that the surfactant used is a castor oil-ethylene oxide adduct wherein there is more than 20 moles of ethylene oxide but less than 40 moles of ethylene oxide added to 1 mole of castor oil.