CN114042005B

CN114042005B - Suspension composition containing lamellar liquid crystal and preparation process thereof

Info

Publication number: CN114042005B
Application number: CN202111324185.8A
Authority: CN
Inventors: 陈国静; 孙吉龙; 李泽勇; 刘康; 周月华
Original assignee: Guangzhou Tinci Materials Technology Co Ltd
Current assignee: Guangzhou Tinci Materials Technology Co Ltd
Priority date: 2021-11-10
Filing date: 2021-11-10
Publication date: 2023-09-08
Anticipated expiration: 2041-11-10
Also published as: CN114042005A

Abstract

The invention belongs to the field of new materials, and in particular relates to a preparation process of a suspension composition containing lamellar liquid crystal, which comprises the following steps: step 1: sequentially adding an anionic surfactant, alcohols, a nonionic surfactant and a proper amount of deionized water into a reactor, heating and stirring the system until the system is clear; step 2: heating the mixture obtained in the step 1 to a first temperature, adding a crystallization aid, and stirring for a period of time in a heat-preserving manner; step 3: adding the cationic polymer pre-dispersed with water, stirring for 3-5min, cooling to a second temperature, stirring at a low speed of not more than 400rpm, and maintaining the temperature for a period of time; by adopting the preparation process, the composition with a layered liquid crystal network structure and a large number of maltese cross patterns can be obtained, and good suspension capability can be provided for particles in the system. In addition, the invention also provides a suspension composition containing lamellar liquid crystal, which is obtained based on the process.

Description

Suspension composition containing lamellar liquid crystal and preparation process thereof

Technical Field

The invention relates to the field of new materials, in particular to a suspension composition containing lamellar liquid crystal and a preparation process thereof.

Background

Shampoo is a complex composition, and the system contains both oil-soluble and water-soluble substances and various granular components, such as antidandruff agent ZPT, silicone oil granules and the like. Such particles tend to float or settle in the system due to density differences, making the composition unstable. To improve the stability in the system, one or more suspension stabilizers have to be added.

Both suspending systems, carbomers and pearlescent flakes, are widely used, but both systems have certain limitations. The suspension performance of the carbowave system is high, but the system compatibility is lower, and the foam is influenced. The compatibility of the pearlitic system is high, but the appearance of the product can be directly influenced, the dry and wet hair effect of the product is changed, and the temperature which the pearlitic system product can bear is low.

The invention patent CN 111135109.A is a composition containing a liquid crystal solid structure, which discloses a method for suspending particles in a system by using a liquid crystal solid structure. However, the liquid crystal structure is radial-shaped like an octopus or a line, and is not a common lamellar liquid crystal structure. Even so, no specific preparation method is disclosed in its entirety.

The invention patent CN1181006a discloses a stress stable lathering skin cleansing liquid composition comprising, based on the weight of the liquid composition, (a) about 0.5 to 10 parts of a crystalline hydroxyl containing stabilizer, such as trihydroxystearin; (b) about 1 to about 30 parts of a lipid skin moisturizer; (c) About 5 to 30 parts of a surfactant whose combined CMC (critical micelle concentration) balances a surface tension value of 15 to 50; and (d) water; wherein the stress stable lathering skin cleansing liquid composition has a Lipid Deposition Value (LDV) of from about 5 to 100, and wherein the composition is stable for at least two weeks at 100°f.

Reference is made to page 17 of the description, which comprises the following process steps: adding crystallization aid first and then adding various surface activities.

It has been verified that this process is not feasible if a liquid crystal material in the pattern of a maltese cross is to be produced.

CN101517060a discloses an aqueous structured surfactant composition comprising an anionic surfactant selected from the group consisting of isethionates, taurates, sarcosinates and mixtures thereof; and electrolytes, and which are useful in personal care applications.

Reference is made to page 40 of the specification, and the preparation method is prepared by a one-pot method, and the specific order of addition and the like are not limited.

The invention aims to solve the technical problems that: how to prepare a composition with a layered liquid crystal network structure and a large amount of maltese cross patterns, so as to provide good suspending capability for particles in the system.

Disclosure of Invention

One of the purposes of the present invention is to provide a process for preparing a suspension composition containing lamellar liquid crystals. By adopting the preparation process, the composition with a layered liquid crystal network structure and a large number of maltese cross patterns can be obtained, and good suspension capability can be provided for particles in the system.

In addition, the invention also provides a suspension composition containing lamellar liquid crystal, which is obtained based on the process.

In order to achieve the above object, the present invention provides a process for preparing a suspension composition containing lamellar liquid crystals, comprising the steps of:

step 1: sequentially adding an anionic surfactant, alcohols, a nonionic surfactant and a proper amount of deionized water into a reactor, heating and stirring the system until the system is clear;

the anionic surfactant is one or more of fatty acyl methyl taurate, sodium lauroyl methyl hydroxyethyl sulfonate, AES and amino acid anionic surfactant; the alcohol is at least one of polyalcohol and higher fatty alcohol;

wherein, more preferably, the polyalcohol is at least one of propylene glycol, 1, 3-butanediol, dipropylene glycol and glycerol; the higher fatty alcohol is at least one of dodecanol, tetradecanol, hexadecanol, octadecanol and icosanol. The alcohols can interact with the surfactant to reduce the interfacial energy between crystallization of the crystallization aid and the solution, promote the formation of crystallization nuclei in the cooling process and promote the formation of liquid crystal forms.

In the mixture obtained in the step 1, the anionic surfactant is 18-28% of the total weight of the mixture;

the key of the step is as follows: the apparent concentration of anions in the mixture is controlled to be 18-28%, no liquid crystal is generated in the subsequent process when the concentration is lower than the range, the concentration is too thick, and the subsequent process cost is high;

step 2: heating the mixture obtained in the step 1 to a first temperature, adding a crystallization aid, and stirring for a period of time in a heat-preserving manner; the first temperature is 3-8 ℃ higher than the melting point of the crystallization aid;

the crystallization aid is at least one of trihydroxystearin, glyceryl tristearate, 12-hydroxystearic acid, glyceryl hydroxystearate and hydrogenated lecithin;

trihydroxystearin is preferred. The crystallization aid is used as a main component for forming the liquid crystal form and participates in the formation of the whole liquid crystal form in the composition. The crystallization aid is solid grease with higher melting point and is difficult to dissolve in water. After it is melted at high temperature, it slowly precipitates with decreasing temperature, and gradually forms a solid state. The formation of liquid crystals requires firstly ensuring that the crystallization aid is sufficiently solubilised at high temperature to form a suitable crystalline dispersion and then slowly precipitates with the reduction of temperature, but because of intermolecular van der Waals forces between the crystallization aid molecules and the surfactant in the system, the interaction of the crystallization aid molecules and the surfactant forms a solid substance attached to surfactant micelles, and the substance is between the solid state and the liquid state, namely the liquid crystal form, and a visible maltese cross pattern can be seen by using a polarizing microscope. If the solubilization is insufficient in the early stage, the trihydroxystearin becomes a large number of tiny crystals to be accumulated in the system.

Step 3: adding the cationic polymer pre-dispersed with water, stirring for 3-5min, cooling to a second temperature, stirring at a low speed of not more than 400rpm, and maintaining the temperature for a period of time; the second temperature is 15-25 ℃ lower than the melting point of the crystallization aid;

in this step, care should be taken to: 1. controlling the apparent concentration of anions in the mixture at 18-28%;2. stirring too fast at the second temperature will destroy the liquid crystal structure; 3. for different crystallization aids, the temperature can be controlled between 50 and 70 ℃, and the specific value is 15 to 25 ℃ lower than the melting point of the crystallization aid;

in the mixture obtained in the step 3, the anionic surfactant is 18-28% of the total weight of the mixture;

the dosages of the anionic surfactant, the alcohols, the nonionic surfactant, the crystallization aid and the cationic polymer are respectively 6-20%, 0.1-3%, 0.5-5%, 0.1-1% and 0.1-4% of the total weight of the suspension composition; preferably, it is: 6-8%, 0.3-2.7%, 0.5-3%, 0.1-1%, 0.3-2%;

preferably, AES may be selected as: sodium laureth sulfate, sodium myristyl alcohol polyoxyethylene ether sulfate, and at least one of sodium palmitoyl alcohol polyoxyethylene ether sulfate;

the fatty acyl methyl hydroxyethyl sodium sulfonate is at least one of lauroyl methyl hydroxyethyl sodium sulfonate, cocoyl methyl hydroxyethyl sodium sulfonate and myristoyl methyl hydroxyethyl sodium sulfonate;

the amount of anionic surfactant is preferably 6-10%; more preferably 6-8%;

in the preparation process of the suspension composition containing the lamellar liquid crystal, the fatty acyl methyl taurate is at least one of sodium methyl cocoyl taurate, sodium methyl lauroyl taurate and sodium methyl myristoyl taurate; the fatty acyl methyl taurate is at least one of cocoyl methyl taurate sodium taurate, lauroyl methyl taurate sodium taurate and myristoyl methyl taurate sodium taurate.

More preferably, the cocoyl methyl taurine sodium taurine surfactant is milder, moderate in stacking parameter and moderate in emulsifying capacity, and can interact with other auxiliary surfactants to form a proper micelle structure, so that the auxiliary crystallization agent can be well solubilized and dispersed under the high-temperature condition, and a synergistic effect is generated, and the formation of a liquid crystal form is promoted.

In the preparation process of the suspension composition containing the lamellar liquid crystal, the nonionic surfactant is at least one of alkyl glucoside, fatty acyl monoethanolamine and fatty glyceride.

The alkyl glucoside is one of decyl glucoside, lauryl glucoside, myristyl glucoside and stearic acid glucoside. The fatty acyl monoethanolamine is one of cocoamide MEA and lauramide MEA. The fatty glyceride is one of cocoyl glyceride, lauric glyceride, myristyl glyceride and stearic glyceride

Fatty acyl monoethanolamines are preferred. The nonionic surfactant can help to lower the melting point of the crystallization aid, reduce the difficulty of process operation and help to solubilize the crystallization aid under high temperature conditions. The crystallization aid is uniformly dispersed, and the crystallization aid is compounded with taurine surfactant to realize synergistic effect, so that the crystallization aid is favorable for precipitation of liquid crystal forms.

In the preparation process of the suspension composition containing the lamellar liquid crystal, the cationic polymer is a polyquaternary ammonium salt cationic polymer or cationic guar gum.

The polyquaternary ammonium salt is at least one of polyquaternary ammonium salt-10, polyquaternary ammonium salt-4, polyquaternary ammonium salt-47 and polyquaternary ammonium salt-22, preferably polyquaternary ammonium salt-10.

The cationic guar gum is one of guar hydroxypropyl trimethyl ammonium chloride and hydroxypropyl guar hydroxypropyl trimethyl ammonium chloride, preferably guar hydroxypropyl trimethyl ammonium chloride.

Cationic polymers provide conditioning primarily. If it has a high charge, it is more advantageous to drive the liquid crystal structure, but excessively strong molecular forces can lead to formulation compatibility and stability problems such as flocculation.

In the preparation process of the suspension composition containing the lamellar liquid crystal, the preparation process further comprises the step 4:

cooling to below 45deg.C, adding amphoteric surfactant or other residue, adjusting pH, and discharging; the pH is preferably 5.5-6.5;

the amphoteric surfactant may comprise 2-8% by weight of the total suspension composition.

In the preparation process of the suspension composition containing the lamellar liquid crystal, the amphoteric surfactant is at least one of fatty acyl amphoacetate sodium, fatty acyl amphodiacetate sodium, fatty acyl propyl betaine and fatty amide hydroxypropyl sulfobetaine. Preferred is cocamidopropyl betaine.

The amphoteric surfactant can form a tighter micelle structure with the anionic surfactant in the system, plays a role in thickening and stabilizing bubbles, and further reduces the irritation of the system.

In the preparation process of the suspension composition containing the lamellar liquid crystal, the balance of water in the suspension composition; the remainder is one or more of preservative, pH regulator and essence.

In the preparation process of the suspension composition containing the lamellar liquid crystal, the first temperature is 90-95 ℃ and the second temperature is 65-75 ℃;

in the step 1, the concentration of the anionic surfactant in the mixture in the step 1 is adjusted to 18-28% by using the additive of deionized water;

the temperature in the step 1 is 70-75 ℃;

the stirring time in the step 2 is 10-30min.

In the preparation process of the suspension composition containing the lamellar liquid crystal, the step 3 specifically comprises:

adding the cationic polymer pre-dispersed with water, stirring at 300-450rpm for 3-5min, cooling to the second temperature, stirring at low speed of 400rpm or less, and maintaining the temperature for 20-40min.

Additional description is: deionized water is added in the method of the invention for the most part at the end;

in step 1, adjusting the concentration of the anionic surfactant to a nominal concentration by adding deionized water;

in step 3, deionized water is mainly used for dispersing cationic polymer, and 1-5 parts of deionized water is generally added;

the balance of deionized water is added after step 3, preferably after the temperature is reduced in step 4.

Finally, the invention also provides a suspension composition prepared by the process, which presents a maltese cross pattern when the lamellar phase is observed under a polarizing microscope.

The beneficial effects of the invention are as follows:

the composition disclosed by the invention is added into a hair cosmetic matrix, the liquid crystal form of the composition can be stably existing in a system, and a large number of lamellar liquid crystal network structures (Malta cross patterns) are utilized, namely classical liquid crystal forms, so that good suspending capability is provided for particles in the system.

Drawings

FIGS. 1-2 are liquid crystal microscopes of examples 1-8 and comparative examples 1-2 of the present invention;

FIG. 3 is a graph showing the suspension effect of examples 2 and 4 and comparative examples 1 to 2.

Detailed Description

The following describes the technical scheme of the invention in further detail, but does not limit the invention in any way.

Examples 1 to 5

a. Heating to 70 ℃, sequentially adding each component in A, B, C phase and a small amount of water, and stirring until the solution is clear and transparent; the apparent concentration of anions in the mixture is controlled to be 23%, no liquid crystal is generated in the subsequent process when the concentration is lower than the range, and the subsequent process is too thick;

b. heating to 90-95deg.C, adding phase D, maintaining the temperature and stirring for 20min;

c. adding the E phase pre-dispersed with water, and uniformly stirring for 4min at 400 rpm; cooling to 65deg.C, stirring at low speed (preferably 350 rpm), maintaining the temperature for 30min, and controlling the apparent anion concentration in the mixture at 20%;

d. cooling to below 45deg.C, adding F phase or other rest materials, adjusting pH, and discharging.

Specific formulations are shown in Table 1 below.

Table 1 formulation table

What should be additionally stated is: PEG-120 methylglucdioleate present in the E phase mainly provides thickening effect and does not serve as a main core component of the present invention;

C12-C14 alkyl glucosides in phase F also provide thickening and suspension stabilization; polydimethylsiloxane is a silicone oil which has good stability in a suspended state and is not a main core component of the present invention.

In fig. 3, it is shown that silicone oils exhibit a pronounced delamination phenomenon in unstable systems.

Example 6

a. Heating to 70 ℃, sequentially adding each component in A, B, C phase and a small amount of water, and stirring until the solution is clear and transparent; controlling the apparent concentration of anions in the mixture at 27%;

c. adding the E phase pre-dispersed with water, and uniformly stirring for 4min at the speed of 450 rpm; cooling to 75deg.C, stirring at low speed (preferably 350 rpm), maintaining for 30min, and controlling the apparent anion concentration in the mixture at 23%;

Specific formulations can be found in table 2 below.

Example 7

a. Heating to 70 ℃, sequentially adding each component in A, B, C phase and a small amount of water, and stirring until the solution is clear and transparent; controlling the apparent concentration of anions in the mixture at 24%;

c. adding the E phase pre-dispersed with water, and uniformly stirring for 4min at 400 rpm; cooling to 70deg.C, stirring at low speed (preferably 350 rpm), maintaining the temperature for 30min, and controlling the apparent anion concentration in the mixture at 21%;

Specific formulations can be found in table 2 below.

Example 8

a. Heating to 70 ℃, sequentially adding each component in A, B, C phase and a small amount of water, and stirring until the solution is clear and transparent; the apparent concentration of anions in the mixture is controlled to be 21%, no liquid crystal is generated in the subsequent process when the concentration is lower than the range, the concentration is too thick, and the subsequent process cost is high;

c. adding the E phase pre-dispersed with water, and uniformly stirring for 4min at the speed of 450 rpm; cooling to 65deg.C, stirring at low speed (preferably 350 rpm), maintaining the temperature for 30min, and controlling the apparent anion concentration in the mixture at 18%;

Specific formulations can be found in table 2 below.

Table 2 formulation table

The relevant liquid crystal effect microscopy images of examples 1-8 can be seen with reference to FIGS. 1-2.

Examples 9 to 11

Examples 9-11 refer to the preparation process flow of example 1, the formulation of which is shown in Table 3 below:

table 3 recipe table

What should be additionally stated is: the experimental range of the amount of the anionic surfactant of examples 1-11 of the present invention only verifies 6-8%; however, in the practical laboratory experiment process, we verify the relevant conditions that the total amount of the anions expressed in terms of 10%, 15% and 20% can generate corresponding liquid crystal phases; the reason why the amount of 6-8% is only exemplified in this example is that the anionic surface activity shown in this example is the solid content weight, the anionic surface activity marked in the package of the commercial product is the non-solid content amount, and the amount of 6-8% in this example corresponds to the amount of 15-25% of the anionic surface activity of the commercial product; the selection of the amount of 10%, 15% and 20% of the anions in terms of surface activity is not commercially significant in market products, mainly is too costly, and if the anions are used according to the amount, the solid content of the finished product is far more than 30%, and the finished product has no commercial value.

In examples 1 to 11, sodium methyl cocoyl taurate, sodium methyl lauroyl taurate and sodium cocoyl taurate in fatty acyl methyl taurate were verified, and other specific activities of taurates and fatty alcohol polyoxyethylene ether sodium sulfate AES (sodium laureth sulfate and sodium palmitoyl polyoxyethylene ether sodium sulfate were verified), and sodium fatty acyl methyl isethionate (sodium lauroyl methyl isethionate was verified), and it was verified that the liquid crystal phase with maltese cross pattern could be successfully prepared with high repetition rate and stability only by the amount and process control according to the present invention.

Alcohols selected from dodecanol, tetradecanol, hexadecanol, octadecanol, eicosyl alcohol, propylene glycol, 1, 3-butanediol, dipropylene glycol, glycerol are all possible, and in the range of 0.5-5% the selection does not affect the formation of a liquid crystal phase of the maltese cross pattern.

According to the invention, other additives such as stability, thickening property, color improvement, smell improvement and the like can be optionally added according to the requirements.

Comparative example 1

The formulation was identical to example 1;

the technological process is as follows:

a. heating to 70 ℃, sequentially adding each component in A, B, C phase and a small amount of water, and stirring until the solution is clear and transparent; controlling the apparent concentration of anions in the mixture at 23%;

b. adding the E phase pre-dispersed with water, and uniformly stirring for 4min at 400 rpm; cooling to 65deg.C, stirring at low speed (preferably 250 rpm), and maintaining for 30min, wherein the apparent concentration of anions in the mixture is controlled at 20%

c. Heating to 93 ℃, adding phase D, and stirring for 20min;

Referring to fig. 2, there is no liquid crystal structure (a large amount of fine luminescent crystals are present under polarized light).

Comparative example 2

The formulation was identical to example 1;

the technological process is as follows:

a. heating to 70 ℃, sequentially adding each component in A, B, C phase and a large amount of water, and stirring until the solution is clear and transparent; controlling the apparent concentration of anions in the mixture at 15%;

b. heating to 93 ℃, adding phase D, and stirring for 20min;

c. adding the E phase pre-dispersed with water, and uniformly stirring for 4min at 400 rpm; cooling to 65deg.C, stirring at low speed (preferably 250 rpm), maintaining the temperature for 30min, and controlling the apparent anion concentration in the mixture at 13%;

Referring to fig. 2, the concentration of anion activity of adjustment step 1 was lower than 18% as observed: no liquid crystal structure (a large amount of fine luminescent crystals are present under polarized light).

Application example 1

The application formulation suspension test was performed for examples 1-8 and comparative examples 1-2, and the specific results are shown in Table 3.

TABLE 3 results of suspension Performance test

Fig. 3 is a photograph of a portion of a sample from a suspension test.

As can be seen from Table 3 and FIG. 3, examples 1-8 of the present invention all have good liquid crystal stability and storage stability.

To achieve this effect, attention must be paid to control the following factors:

in addition to controlling the proper formulation, it is critical to control the initial apparent concentration, the order of material addition, and the magnitude of the temperature increase, as to whether a stable liquid crystal system can be formed.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims

1. A process for preparing a suspension composition comprising lamellar liquid crystals, characterized by the steps of:

the anionic surfactant is one or more of fatty acyl methyl taurate, fatty acyl methyl hydroxyethyl sodium sulfonate, AES and amino acid anionic surfactant; the alcohol is at least one of polyalcohol and higher fatty alcohol;

in the mixture obtained in step 1, the amount of the anionic surfactant is 18-28% of the total weight of the mixture obtained in step 1;

the amount of the anionic surfactant in the mixture obtained in the step 3 is 18-28% of the total weight of the mixture obtained in the step 3;

step 4: cooling to below 45 ℃, adding an amphoteric surfactant, other remainder and the balance of water, adjusting pH, and discharging to obtain a suspension composition;

the dosages of the anionic surfactant, the alcohols, the nonionic surfactant, the crystallization aid and the cationic polymer are respectively 6-20%, 0.1-3%, 0.5-5%, 0.1-1% and 0.1-4% of the total weight of the suspension composition;

the cationic polymer is a polyquaternary ammonium salt cationic polymer or cationic guar gum.

2. The process for preparing a lamellar liquid crystal-containing suspension composition according to claim 1, characterized in that the fatty acyl methyl taurate is at least one of sodium methyl cocoyl taurate, sodium methyl lauroyl taurate, sodium methyl myristoyl taurate; the fatty acyl methyl taurate is at least one of cocoyl methyl taurate sodium taurate, lauroyl methyl taurate sodium taurate and myristoyl methyl taurate sodium taurate; AES is at least one of sodium laureth sulfate, sodium myristyl alcohol polyoxyethylene ether sulfate and sodium palmitoyl alcohol polyoxyethylene ether sulfate; the fatty acyl methyl hydroxyethyl sodium sulfonate is at least one of lauroyl methyl hydroxyethyl sodium sulfonate, cocoyl methyl hydroxyethyl sodium sulfonate and myristoyl methyl hydroxyethyl sodium sulfonate.

3. The process for preparing a lamellar liquid crystal-containing suspension composition according to claim 1, characterized in that the nonionic surfactant is at least one of alkyl glycoside, fatty acyl monoethanolamine, fatty glyceride, the alcohol is at least one of polyhydric alcohol, higher fatty alcohol, wherein the polyhydric alcohol is at least one of propylene glycol, 1, 3-butanediol, dipropylene glycol, glycerin; the higher fatty alcohol is at least one of dodecanol, tetradecanol, hexadecanol, octadecanol and icosanol.

4. The process for preparing a lamellar liquid crystal containing suspension composition according to claim 1, characterized in that the amount of anionic surfactant, alcohols, nonionic surfactant, crystallization aid, cationic polymer is 6-8%, 0.3-2.7%, 0.5-3%, 0.1-1%, 0.3-2% of the total weight of the suspension composition, respectively.

5. The process for preparing a suspension composition containing lamellar liquid crystals according to claim 1, characterized in that the amphoteric surfactant corresponds to 2-8% of the total weight of the suspension composition.

6. The process for preparing a lamellar liquid crystal containing suspension composition in accordance with claim 5, characterized in that the amphoteric surfactant is at least one of sodium fatty acyl amphoacetate, sodium fatty acyl amphodiacetate, fatty acyl propyl betaine, fatty amidohydroxypropyl sulfobetaine.

7. The process for preparing a suspension composition containing lamellar liquid crystals as claimed in claim 5, characterized in that the other remainder is one or more of preservative, pH regulator, essence.

8. The process for preparing a suspension composition containing lamellar liquid crystals according to claim 1, characterized in that the first temperature is 90-95 ℃ and the second temperature is 65-75 ℃;

in the step 1, the addition amount of deionized water is preferably adjusted to 18-28% of the concentration of the anionic surfactant in the mixture in the step 1;

the heating temperature in the step 1 is 70-75 ℃;

the stirring time in the step 2 is 10-30min.

9. The process for preparing a suspension composition containing lamellar liquid crystals according to claim 1, characterized in that step 3 is specifically:

10. A suspension composition prepared by the process of any one of claims 1-9, wherein the lamellar phase exhibits a maltese cross pattern when viewed under a polarizing microscope.